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Addition and subtraction with significant figures | Decimals | Pre-Algebra | Khan Academy

Video vocabulary

equal

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US / 'i:kwəl /

UK / ˈikwəl /

A1
  • adjecitve
  • Same in shape, size, or number
  • verb
  • To add up or be the same as

measure

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US / ˈmeʒə(r) /

UK / ˈmɛʒɚ /

A1
  • noun
  • Plan to achieve a desired result
  • Tool used to calculate the size of something
  • verb
  • To determine the value or importance of something
  • To calculate size, weight or temperature of

neat

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US / ni:t /

UK / nit /

A2
  • adjecitve
  • That you approve of; cool
  • (Of alcohol) not weakened with water or a mixer
  • Not messy; clean and orderly; simple and effective

tall

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US / tɔ:l /

UK / tɔl /

A1
  • adjecitve
  • High in height

now

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US / naʊ /

UK / naʊ /

A1
  • adverb
  • At the present time or moment
  • Right away or in the next possible moment
  • Used to refer to something that just happened
  • Time between the present and a moment in the past
  • conjunction
  • Resulting from or because of something

color

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US / 'kʌlə(r) /

UK / ˈkʌlɚ /

A1
  • noun
  • Quality of things you can see, e.g. red, blue
  • Pink or red in your face, e.g. after being ill
  • The shade of someone's skin e.g. black, or yellow
  • verb
  • To change or affect someone's opinion
  • To make something colorful using colored pencils

maybe

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US / ˈmeɪbi /

UK / ˈmebi /

A1
  • adverb
  • Possibly but not certainly; perhaps

our

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US / 'aʊə(r) /

UK / aʊr /

A1
  • determiner
  • Belonging to us

not

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US / nɒt /

UK / nɑt /

A1
  • adverb
  • Word indicating the negative
  • (Used to form the negative of verbs)

radio

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US / ˈreɪdiəʊ /

UK / ˈreɪdioʊ /

A2
  • adjecitve
  • Concerning the broadcasting of sound
  • noun
  • System of sending/receiving signals through air
  • Device to listen to broadcast programs, messages
  • verb
  • To broadcast a message to be heard by radio

can

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US / kæn /

UK / kən,kæn /

A1
  • noun
  • A metal container for storing food
  • other
  • Able to; have the skill to; have the time to
  • verb
  • To have permission to
  • To be possible to do
  • To preserve food by sealing it in a metal container

become

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US / bɪ'kʌm /

UK / bɪˈkʌm /

A1
  • verb
  • To begin to be; grow to be; develop into
  • To be suitable for a particular job or role

sense

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US / sens /

UK / sɛns /

A1
  • noun
  • Certain mental feeling or emotion
  • Normal or clear state of mind
  • Meaning of a particular word, phrase or text
  • verb
  • To perceive using sight, sound, taste touch etc.
  • To recognize the presence of something

represent

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US / ˌreprɪ'zent /

UK / ˌrɛprɪˈzɛnt /

A2
  • verb
  • To depict art objects, figures, scenes; to portray
  • To show or describe something in a particular way
  • To act on behalf of others in government
  • To act or speak for another person or other people

round

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US / raʊnd /

UK / raʊnd /

A1
  • adjecitve
  • Being in the shape of a circle or ball
  • Consisting of curved and not straight lines
  • Somewhat fat or curved in physical appearance
  • Being a whole number, not a fraction, decimal
  • adverb
  • From beginning to end (e.g. of the year)
  • noun
  • One of the three-minute periods in boxing
  • Drinks bought by one person for a group
  • Series regular visits, routes, or stops at places
  • Single shot or bullet fired from a gun
  • An object with a circular shape
  • One stage in a series of games, e.g. football
  • One's turn in a game such as cards
  • preposition
  • Going around
  • verb
  • To cause or make a circular or curved shape
  • To go or pass around the bend or corner
  • To change from a fraction to nearest whole number

but

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US / bət /

UK / bʌt,bət /

A1
  • conjunction
  • Used before you say something different, opposite

cut

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US / kʌt /

UK / kʌt /

A1
  • noun
  • Act/instance of reducing the size or amount of
  • Small opening made using a sharp object, knife
  • A wound on someone's skin caused by a sharp object
  • verb
  • To reduce the size or amount of something
  • To use knife or scissors to divide, open surfaces

apply

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US / ə'plaɪ /

UK / əˈplaɪ /

A1
  • verb
  • To spread a substance or liquid over a surface
  • To commit your time and effort to doing something
  • To make something useful in a certain situation
  • To be relevant for a situation
  • To ask formally for (job, permission etc.)

good

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US / ɡʊd /

UK / ɡʊd /

A1
  • adjecitve
  • Proper, appropriate or right
  • (Of an amount) enough; plenty
  • Excellent; high quality
  • Acting well or properly; of moral character
  • In a positive or happy emotional state
  • noun
  • Advantage or benefit

zero

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US / ˈzɪərəʊ /

UK / ˈzɪroʊ /

A1
  • noun
  • Temperature when water turns to ice
  • number
  • Number 0
  • verb
  • To set a scale or other device to show 0

want

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US / wɔnt /

UK / wɑnt, wɔnt /

A1
  • noun
  • Something you desire or wish for
  • State or condition of poverty
  • verb
  • To desire or wish for something; hope for a thing

seven

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US / ˈsevn /

UK / ˈsɛvən /

A1
  • number
  • Number 7

sum

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US / sʌm /

UK / sʌm /

A2
  • noun
  • Amount when all is added together; total
  • verb
  • To add two or more numbers together; total

significant

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US / sɪgˈnɪfɪkənt /

UK / sɪɡˈnɪfɪkənt /

A2
  • adjecitve
  • Large enough to be noticed or have an effect
  • Having meaning; important; noticeable
  • (Statistics) being clearly different

video

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US / 'vɪdɪəʊ /

UK / ˈvɪdiˌo /

A2
  • adjecitve
  • Of a moving film, with sound
  • noun
  • Recording capturing action with sound
  • verb
  • To make a moving film of, with sound

blue

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US / blu: /

UK / blu /

A1
  • adjecitve
  • Color of the clear sky
  • Feeling sad or down

would

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US / wʊd /

UK / wʊd /

A1
  • other
  • Used to indicate something imagined
  • Used to ask or request something politely
  • Verb used to indicate possibility, request etc.
  • Used to indicate a preference
  • Used to indicate a reaction
  • Indicates something that occurred repeatedly
  • Used to indicate willingness or ability to do

really

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US / ˈri:əli /

UK / ˈriəˌli, ˈrili /

A1
  • adverb
  • Used to stress something that is said; definitely
  • In a true or accurate manner
  • Very

and

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US / ənd /

UK / ənd, ən,ænd /

A1
  • conjunction
  • Used to refer to two or more things
  • Plus; in addition; on top of that
  • Used to introduce an action that follows another

guy

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US / ɡaɪ /

UK / ɡaɪ /

A1
  • noun
  • Man; boy; any person

another

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US / əˈnʌðə(r) /

UK / əˈnʌðɚ /

A1
  • adjecitve
  • One more, but not this
  • determiner
  • One more added
  • pronoun
  • One more (thing)

hey

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US / heɪ /

UK / he /

A1
  • exclamation
  • What you say when you want someone's attention

sometimes

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US / ˈsʌmtaɪmz /

UK / ˈsʌmˌtaɪmz /

A1
  • adverb
  • Only at certain times; occasionally

real

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US / rɪəl /

UK / ˈriəl, ril /

A1
  • adjecitve
  • Actually existing or happening, not imagined
  • Being important or special

stack

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US / stæk /

UK / stæk /

B1
  • noun
  • A large number or amount of something
  • Large tube through which smoke exits a building
  • verb
  • To arrange cards in a certain order, to cheat
  • To put one thing on top of another, e.g. boxes

out

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US / aʊt /

UK / aʊt /

A1
  • adverb
  • No longer stylish (e.g. fashion)
  • Away from home, business, or the usual place
  • In a direction/movement away from inside or center
  • noun
  • Act when a batter cannot continue playing
  • verb
  • To tell people a secret

over

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US / 'əʊvə(r) /

UK / ˈovɚ /

A1
  • adverb
  • Finished; no longer happening
  • Towards the ground/away from a standing position
  • noun
  • A set of six consecutive balls bowled in cricket
  • other
  • Finished
  • preposition
  • Showing the relation when a thing is above another
  • On or covering something
  • Above or across something
  • More than you need
  • From one side to the other
  • In the direction of; toward

overwhelm

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US / ˌəʊvəˈwelm /

UK / ˌoʊvərˈwelm /

B1
  • verb
  • To defeat something or someone completely
  • To affect someone emotionally in a strong way
  • To cause to have too much to handle (e.g. work)

literally

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US / ˈlɪtərəli /

UK / ˈlɪtərəli /

B1
  • adverb
  • So as to express the exact meaning of something
  • Used to say something is true, even if unlikely

precision

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US / prɪˈsɪʒn /

UK / prɪˈsɪʒən /

A2
  • adjecitve
  • Performed in a very careful, detailed manner
  • noun
  • Quality of being very accurate and exact

particular

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US / pəˈtɪkjələ(r) /

UK / pɚˈtɪkjəlɚ, pəˈtɪk- /

B2
  • adjecitve
  • One specific (one)
  • Having firm ideas about what is desirable
  • Being special or more than is typical

think

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US / θɪŋk /

UK / θɪŋk /

A1
  • verb
  • To have an idea about something without certainty
  • To have an idea, opinion or belief about something

rightfully

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US / 'raɪtfəlɪ /

UK / ˈraɪtfəlɪ /

B1
  • adverb
  • By right; as decided by moral or legal right

height

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US / haɪt /

UK / haɪt /

A2
  • noun
  • Distance of something from the bottom to the top

only

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US / ˈəunli /

UK / ˈonli /

A1
  • adverb
  • Just one; just that amount or thing; not more than
  • Not very important or serious
  • Just that type of thing, person
  • Short time ago; not before a certain time
  • conjunction
  • Except; but

put

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US / pʊt /

UK / pʊt /

A1
  • phrasal verb
  • to make a light stop shining by pressing or moving a switch
  • verb
  • To move or place a thing in a particular position
  • To rate something in importance or value
  • To write or say something in a certain manner

two

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US / tu: /

UK / tu /

A1
  • number
  • 2

something

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US / ˈsʌmθɪŋ /

UK / ˈsʌmθɪŋ /

A1
  • adverb
  • In some degree or measure
  • noun
  • a person or thing of some value or consequence
  • pronoun
  • Thing that is not yet known or named
  • Approximately

antenna

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US / ænˈtenə /

UK / ænˈtɛnə /

B2
  • noun
  • Antenna; device for receiving radio/ TV signal

also

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US / 'ɔ:lsəʊ /

UK / ˈɔlso /

A1
  • adverb
  • In addition; too; in a similar way

kind

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US / kaɪnd /

UK / kaɪnd /

A1
  • adjecitve
  • In a caring and helpful manner
  • friendly and considerate
  • noun
  • One type of thing

how

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US / haʊ /

UK / haʊ /

A1
  • adjecitve
  • To what degree? in what amount?
  • adverb
  • (Used to explain the way to do something)
  • exclamation
  • For what purpose or reason?
  • (Used to ask someone or something's condition)

you

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US / jʊ /

UK / ju /

A1
  • pronoun
  • Person someone is speaking or writing to
  • Person or people in general

this

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US / ðɪs /

UK / ðɪs /

A1
  • adjecitve
  • Used to indicate something already been discussed
  • Used to indicate something happening around now
  • adverb
  • An indication by a physical motion or gesture
  • A specific amount of
  • determiner
  • Person, thing, or idea near you
  • pronoun
  • Person, thing that has already been discussed

entire

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US / ɪn'taɪə(r) /

UK / ɛnˈtaɪr /

A2
  • adjecitve
  • Complete or full; with no part left out; whole

one

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US / wʌn /

UK / wʌn /

A1
  • pronoun
  • You; we; people in general; someone
  • The thing or person previously referred to
  • adjecitve
  • Used to refer to people generally
  • Being a strong example of (something mentioned)
  • number
  • Number 1

other

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US / 'ʌðə(r) /

UK / ˈʌðər /

A1
  • adjecitve
  • A thing different from that mentioned
  • determiner
  • (Something) else; not the first (one)
  • pronoun
  • Being the one and only thing of that category

than

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US / ðən /

UK / ðən /

A1
  • conjunction
  • Used to compare two things that are not equal

answer

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US / 'ɑ:nsə(r) /

UK / ˈænsɚ /

A1
  • noun
  • Reply to a question someone asks
  • Solution to a problem or test question
  • verb
  • To reply to a question someone asks
  • To solve a test question or a problem

less

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US / les /

UK / lɛs /

A1
  • adjecitve
  • Smaller in amount or degree
  • adverb
  • To a smaller degree
  • noun
  • A smaller amount
  • preposition
  • With the subtraction of

let

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US / let /

UK / lɛt /

A1
  • verb
  • To allow someone to do something
  • Introducing a suggestion to do something together
  • To rent a house, etc. to others

little

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US / 'lɪtl /

UK / ˈlɪtl /

A1
  • adjecitve
  • Being short in length of time
  • Not great in size, amount, or degree; small
  • Being very young or younger than others
  • adverb
  • By an amount or degree that is not very much
  • Not often; rarely
  • noun
  • A person's name

might

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US / maɪt /

UK / maɪt /

A1
  • other
  • Used to politely request an action
  • Used to express that something could happen
  • Power, strength, force or influence

the

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US / ðə /

UK / ðə /

A1
  • article
  • Used to refer to something already mentioned
  • Used to show there is only one of something
  • determiner
  • Used to describe all of a family

below

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US / bɪ'ləʊ /

UK / bɪˈlo /

A1
  • preposition
  • In a lower position, place, or level

order

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US / 'ɔ:də(r) /

UK / ˈɔrdɚ /

A1
  • noun
  • Religious or social group, as of nuns
  • Instructions to others to do what you want
  • State in which things are neat and organized
  • What you ask to buy, e.g. food in restaurant
  • Social or political control of an area
  • verb
  • To put things in a sequence, e.g. a, b, c
  • To give instructions to others to do what you want
  • To ask for something you want to buy, e.g. a meal

make

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US / meɪk /

UK / mek /

A1
  • noun
  • Product made by a particular company; brand
  • verb
  • To arrange or prepare something e.g. dinner
  • To get to (a place) on time
  • To gain the status of (teacher, lawyer, etc.)
  • To create something by putting things together
  • To earn a certain amount of money at a job
  • To cause or force a person to do something
  • To cause something to happen or be formed

numerical

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US / nju:ˈmerɪkl /

UK / nu:ˈmerɪkl /

B2
  • adjecitve
  • Concerning or involving numbers

level

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US / 'levl /

UK / ˈlɛvəl /

A2
  • adjecitve
  • (Sports) equal to another
  • Being steady and determined (e.g. a voice)
  • noun
  • Specific height of something
  • Amount of ability you have compared to others
  • Floor or deck within a building
  • Tool used to determine if something is lying flat
  • verb
  • To aim a gun at someone
  • To destroy a building; flatten an area completely
  • To make things flat or even
  • To make a score equal to another, in sports

able

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US / 'eɪbl /

UK / ˈebəl /

A2
  • adjecitve
  • Skilled; good at something
  • Having the ability to do something

subtraction

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US / səb'trækʃn /

UK / səbˈtrækʃən /

B2
  • noun
  • Act of taking one value away from another

three

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US / θri: /

UK / θri /

A1
  • number
  • Number 3

notation

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US / nəʊ'teɪʃn /

UK / noˈteʃən /

C2
  • noun
  • Set of written signs are used in music or math

place

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US / pleɪs /

UK / ples /

A1
  • noun
  • Particular location, area or region
  • verb
  • To put someone in a particular type of situation
  • To put something in a certain location or position

access

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US / 'ækses /

UK / ˈæksɛs /

A2
  • noun
  • Way to enter a place, e.g. a station or stadium
  • verb
  • To be able to use or have permission to use

block

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US / blɒk /

UK / blɑk /

A2
  • noun
  • Solid piece of material used for building
  • A piece of wood, chocolate etc.
  • Hard piece of wood, stone etc. with straight edges
  • Building made up of offices or apartments
  • Area of a city divided by four streets
  • verb
  • To stop from going forward or making progress

down

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US / daʊn /

UK / daʊn /

A1
  • adjecitve
  • Being sad, sick, or unhappy
  • Not operating, working, or functioning as expected
  • adverb
  • In a sitting or lying position
  • Towards or on the ground, floor, or bottom
  • Written or copied onto a piece of paper or book
  • noun
  • A period of play in American Football
  • The soft, smooth hairs that cover a bird's body
  • preposition
  • Along something's path, course, or direction
  • Going from a higher position to a lower position
  • verb
  • To eat or drink very quickly and without stopping

anymore

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US / 'enɪmɔ: /

UK / ˌɛniˈmɔr, -ˈmor /

A2
  • adverb
  • No longer; no more

then

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US / ðen /

UK / ðɛn /

A1
  • adverb
  • A time that is not now
  • Following another thing in time or arrangement
  • Following on reasonably from what was just stated
  • At that time, not now

least

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US / li:st /

UK / list /

A1
  • adverb
  • In the smallest or lowest way
  • noun
  • Something that is of the lowest or smallest degree

right

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US / raɪt /

UK / raɪt /

A1
  • adjecitve
  • Correct or true
  • The south side of you looking at the rising sun
  • adverb
  • Exactly in a place or time
  • Being appropriate for a particular event
  • In a straight or direct manner
  • noun
  • Something you are legally or morally allowed to do
  • Ideal of what is just and good
  • Political view based on conservatism
  • verb
  • To fix something previously wrong or unjust
  • To make upright, as a boat that has turned over

again

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US / ə'ɡen /

UK / əˈɡɛn /

A1
  • adverb
  • One more time, once more

about

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US / ə'baʊt /

UK / əˈbaʊt /

A1
  • adverb
  • To be ready to; going to
  • Nearly; approximately; roughly
  • Near; next to; close to
  • In every direction; in the area of
  • preposition
  • Concerning or of (a topic)

care

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US / keə(r) /

UK / kɛr /

A1
  • noun
  • Treatment you receive for your health or safety
  • Something that a person worries about
  • verb
  • To feel interest, concern, or worry
  • To look after someone or something

different

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US / ˈdɪfrənt /

UK / ˈdɪfrənt /

A1
  • adjecitve
  • Not of the same kind; unlike other things

even

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US / 'i:vn /

UK / ˈivən /

A1
  • adjecitve
  • Being equal in influence, power, possibility etc.
  • Being divided equally or fairly
  • (Of teams/contest) with similar chances of success
  • Smooth, level, or regular
  • Can be divided by 2; ending in 2, 4, 6, 8, or 0
  • At a regular, equally steady manner
  • Remaining steady and unchanging
  • adverb
  • (When this is surprising) as well; too
  • (Used to compare two things/stress the difference)
  • verb
  • To make something level; to flatten
  • To make something equal

label

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US / 'leɪbl /

UK / ˈlebəl /

A2
  • noun
  • A (luxury) brand owned by a company
  • A word or term used to describe a person, thing
  • A piece of paper or material to identify something
  • verb
  • To use a term to describe, often negatively
  • To attach material to identify something

like

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US / laɪk /

UK / laɪk /

A1
  • adjecitve
  • Being equal in status or kind to something else
  • Similar; the same
  • adverb
  • For example
  • preposition
  • Used as a filler; used to ad emphasis
  • In a way similar to the way something is done
  • Such as; for example
  • verb
  • To want to
  • To find something pleasing; to prefer something

second

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US / 'sekənd /

UK / ˈsɛkənd /

A1
  • adjecitve
  • 2nd; the one following first
  • noun
  • Unit of time; one sixtieth of a minute
  • Short period of time that you wait for someone
  • (Do) soon

what

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US / wɒt /

UK / hwɑt, hwʌt, wɔt, wʌt,hwət, wət /

A1
  • pronoun
  • Thing or things that; the same kind as
  • Used to emphasize something you are about to say
  • adjecitve
  • Used to refer to a particular amount, or number
  • Used to place emphasis on a particular quality
  • adverb
  • To a certain degree
  • determiner
  • Question words used for asking for information
  • exclamation
  • Used to express excitement, shock, or surprise
  • Used to ask people to repeat something they said

that

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US / ðæt /

UK / ðæt, ðət /

A1
  • adjecitve
  • The person or thing being talked about
  • Used to identify something both the speakers know
  • adverb
  • Used to reinforce adjectives and adverbs
  • To such a degree
  • conjunction
  • Used to connect a noun clause
  • Used to introduce an adverbial clause
  • Used to introduce a noun clause
  • determiner
  • Used as a noun to refer to something
  • pronoun
  • Referring an object far away
  • Used to refer to the relative pronoun ‘which’

reaction

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US / rɪ'ækʃn /

UK / riˈækʃən /

A2
  • noun
  • Bodily response to a drug or something eaten
  • Feeling or action in response to something

first

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US / fɜ:st /

UK / fɚst /

A1
  • adjecitve
  • 1st; Coming before all others in time or place
  • noun
  • Something that has not happened before
  • Position of the winner of a competition

get

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US / ɡet /

UK / ɡɛt /

A1
  • verb
  • To become affected by illness or disease
  • To begin to feel or understand an emotion or idea
  • To send or bring someone or something home, etc.
  • To go somewhere to obtain something
  • To (cause to) do a particular thing
  • To obtain, receive or be given something
  • To currently have
  • To prepare for use
  • To understand something being said or read

example

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US / ɪgˈzɑ:mpl /

UK / ɪɡˈzæmpəl /

A1
  • noun
  • Thing, person which represents a category

tile

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US / taɪl /

UK / taɪl /

B1
  • noun
  • Squares of hard material to cover floor/roof/wall

nothing

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US / 'nʌθɪŋ /

UK / ˈnʌθɪŋ /

A1
  • noun
  • Item of little or no value, importance, interest
  • Number or value of zero
  • pronoun
  • Not anything, not a single thing

tell

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US / tel /

UK / tɛl /

A1
  • verb
  • To (strongly) advise a person to do something
  • To be able to guess
  • To say or communicate information to someone
  • To inform, but without speaking; indicate
  • To have a negative effect on someone
  • To order someone to do something; command
  • To recognize something based on certain signs
  • To report something to an authority
  • To explain something or teach someone something

number

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US / ˈnʌmbə(r) /

UK / ˈnʌmbɚ /

A1
  • noun
  • Symbols such as 1, 2, 56, 793
  • Particular song or dance performed during a show
  • Total quantity or amount of things
  • verb
  • To put numbers on things
  • To assign a sequence within a group, series, set
  • To claim to be part of a larger group, series, set

great

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US / ɡreɪt /

UK / ɡret /

A1
  • adjecitve
  • Very large in size
  • Very important
  • Very good; fantastic; wonderful
  • adverb
  • Very good; better than before
  • noun
  • Successful and well-admired person

with

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US / wɪð /

UK / wɪð, wɪθ /

A1
  • preposition
  • As an employee of a certain company
  • Against something or someone
  • By using something as a means
  • Due to; because of
  • Including
  • Possessing as a feature
  • Related to
  • (Of the manner/attitude by which you do something)
  • Used to express that people or things are together

have

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US / həv /

UK / hæv /

A1
  • verb
  • To drink, smoke, eat or use something
  • To experience the effects of something
  • To organize an event, or join in an activity
  • To own, possess, or hold something
  • To cause to happen or produce a particular effect

last

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US / lɑ:st /

UK / læst /

A1
  • adjecitve
  • Most recent; the latest
  • The one before
  • adverb
  • Final; with nothing following; after all others
  • Most recent; the latest
  • determiner
  • The one at the end
  • verb
  • To remain or continue for a certain period of time

part

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US / pɑ:t /

UK / pɑ:rt /

A1
  • adjecitve
  • To some degree; half; not fully
  • noun
  • Division of a book
  • Ratio of something, e.g. 3 of gin, 1 of tonic
  • A line in a person's hair, made with a comb
  • Character an actor plays on stage, movie, or TV
  • Some, but not all of a specific thing
  • Role in causing something to happen
  • verb
  • To make a line in a person's hair, by using a comb
  • To move two things apart creating a space
  • To leave someone, or to break off a relationship

behind

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US / bɪˈhaɪnd /

UK / bɪˈhaɪnd /

A1
  • adjecitve
  • Concerning a later or slower time than expected
  • Being in a losing position in a sporting event
  • Being in the past; old fashioned
  • adverb
  • Remaining
  • noun
  • The part of the body that one sits on
  • preposition
  • At or toward the back of someone or something
  • Supporting or helping someone

foot

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US / fʊt /

UK / fʊt /

A1
  • noun
  • Base of something such as a mountain or vase
  • Length of 12 inches or about 25 cm
  • Lowest part of the leg we use to stand on

know

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US / nəʊ /

UK / noʊ /

A1
  • verb
  • To be familiar with a person or place, thing
  • To feel sure or be convinced about something
  • To discover or be aware of something
  • To be able to distinguish
  • To have knowledge of things

could

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US / kəd /

UK / kʊd /

A1
  • other
  • Past form of 'can' to mean have ability
  • Used to ask for something politely, or to offer

precise

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US / prɪ'saɪs /

UK / prɪˈsaɪs /

A2
  • adjecitve
  • (Of language details etc.) Very accurate and exact
  • (Of a time, place, quality) exact
  • Being very careful about how you do things

clear

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US / klɪə(r) /

UK / klɪr /

A1
  • adjecitve
  • Empty; without anything in it or on it
  • Being certain and without doubt
  • Being without any streaks, spots, or cracks
  • Easy to understand; well-explained; obvious
  • adverb
  • Completely; entirely; through the whole of
  • Away from; free from
  • verb
  • To recover from or remove a problem
  • To get rid of the entire contents of
  • To give permission for something to happen
  • To make a place or surface empty by removing
  • To prove that someone is not guilty or to blame

problem

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US / ˈprɒbləm /

UK / ˈprɑbləm /

A1
  • adjecitve
  • Causing trouble
  • noun
  • Something difficult to deal with or causes trouble
  • Question to show understanding of a math concept

draw

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US / drɔ: /

UK / drɔ /

A1
  • noun
  • Something that attracts people to visit a place
  • A lottery or prize
  • Result of a game, contest where the score is equal
  • verb
  • To attract attention to someone or something
  • To get closer to or approach something or someone
  • To influence a person's involvement in something
  • To move an object by pulling
  • To create an image using pen or pencil and paper
  • To take one thing out of a container, etc.
  • (Of 2 teams) to finish a game with the same score

notice

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US / 'nəʊtɪs /

UK / ˈnotɪs /

A1
  • noun
  • Time by when you must leave, e.g. if you are fired
  • Paper with an announcement, e.g. pinned to a board
  • verb
  • To become aware by sight, touch, or hearing

count

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US / kaʊnt /

UK / kaʊnt /

A2
  • noun
  • Number of things added together, e.g. votes
  • With the number of crimes, knockouts, as stated
  • verb
  • To add things together to find the total number
  • To matter or be important
  • To include someone or something in a final number

end

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US / end /

UK / ɛnd /

A1
  • noun
  • The point where a process or activity stops
  • A point that marks the limit of something; finish
  • Goal or desired result
  • The tip, edge or limit of something
  • verb
  • To be the last part of something

see

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US / si: /

UK / si /

A1
  • verb
  • To go on a date with someone
  • To predict whether something is, or will be true
  • To understand what someone says
  • To use your eyes to look at something
  • To visit a place often for sightseeing or pleasure
  • To visit or meet with someone
  • To find out by waiting or looking
  • To watch (a game, movie or TV show)

away

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US / ə'weɪ /

UK / əˈwe /

A1
  • adjecitve
  • Not present
  • adverb
  • Disappear completely
  • Doing something with a lot of energy
  • Not here; far from here; in a different direction
  • To a different area, location

meter

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US / ˈmi:tə(r) /

UK / ˈmitɚ /

A1
  • noun
  • Unit of length equal to 100 cm or about 39 inches
  • Device for measuring things e.g. gas
  • Device to put money into to rent a parking place
  • Rhythm of a poem
  • verb
  • To measure water, etc. when it has to be paid for

world

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US / wɜ:ld /

UK / wɜrld /

A1
  • noun
  • All the humans, events, activities on the earth
  • Political division due to some kind of similarity

properly

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US / ˈprɔpəlɪ /

UK / ˈprɑːpərli /

A2
  • adverb
  • In an appropriate or correct manner

ago

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US / əˈgəʊ /

UK / əˈgoʊ /

A1
  • adverb
  • At a specified length of time in the past

figure

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US / ˈfiɡə /

UK / ˈfɪɡjɚ /

A1
  • noun
  • Your body shape
  • Numbers in a calculation
  • Doll-like thing meant to represent a person
  • Picture or diagram giving information in a text
  • Person who is very important or famous
  • Shape of a person seen indistinctly or in outline
  • Amount that is expressed in numbers
  • verb
  • To appear in a game, play or event
  • To calculate how much something will cost
  • To understand after thinking; work out

way

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US / weɪ /

UK / we /

A1
  • adverb
  • Used to emphasize the amount of something
  • noun
  • Particular aspect of something being thought about
  • One of various choices that could be made
  • Particular existing condition or state
  • (Often long) distance or length of time
  • How something is done
  • Route to go to a place
  • Small street
  • Usual behavior, emotions or habits of someone

their

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US / ðɛː /

UK / ðer /

A1
  • determiner
  • Belonging to them

building

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US / ˈbɪldɪŋ /

UK / ˈbɪldɪŋ /

A1
  • noun
  • A structure with a roof and walls, e.g. a house
  • verb
  • To establish e.g. a reputation, over time
  • To construct a house, office, factory

glue

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US / ɡlu: /

UK / ɡlu /

B1
  • noun
  • Sticky substance used for joining things together
  • verb
  • To join or affix things with glue or paste

work

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US / wɜ:k /

UK / wɚk /

A1
  • adjecitve
  • Activity completed in order to make money
  • noun
  • The product of some artistic or literary endeavor
  • Everything created by an author, artist, musician
  • Activity you do in order to make money
  • Place of employment
  • Final product or result of a some labor or effort
  • verb
  • To bring into a specific state of success
  • To be functioning properly, e.g. a car
  • To do your job in your company or workplace
  • To make an effort to do something
  • To operate a machine or device

show

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US / ʃəʊ /

UK / ʃo /

A1
  • noun
  • False display of love, emotion or action
  • An event for displaying or promoting goods
  • Play, opera or theater production
  • Presentation that is broadcast on TV or radio
  • verb
  • To be easily seen or displayed
  • To display your emotions or feelings
  • To let someone see something; display
  • To explain or teach how something is done
  • To lead someone somewhere; point them to something
  • To prove something to be true, correct
  • To reveal or allow something to be seen

result

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US / rɪ'zʌlt /

UK / rɪˈzʌlt /

A2
  • noun
  • Something produced through tests or experiments
  • Final score of a competition, election or game
  • verb
  • To be the outcome of other causes and effects

error

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US / ˈerə(r) /

UK / ˈɛrɚ /

A2
  • noun
  • Something that is not correct; a mistake

specify

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US / ˈspesɪfaɪ /

UK / ˈspɛsəˌfaɪ /

A2
  • verb
  • To state, name or mention exactly and clearly

they

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US / ðeɪ /

UK / ðe /

A1
  • pronoun
  • Two or more people, animals, or things

very

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US / 'verɪ /

UK / ˈvɛri /

A1
  • adjecitve
  • Concerning a large degree or amount
  • adverb
  • A lot; much; many
  • Used to stress or emphasize a noun

all

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US / ɔ:l /

UK / ɔl /

A1
  • adverb
  • Completely; totally
  • determiner
  • Being every one of something
  • pronoun
  • 100% of something; the complete amount

top

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US / tɒp /

UK / tɑp /

A1
  • adjecitve
  • Being good or great; excellent
  • Being the most in degree or quality
  • noun
  • Item of clothing covering shoulders to waist, hips
  • A cover or lid
  • Part (e.g. road) that is the furthest away
  • Highest or upper part or point of something
  • Best or highest status or position
  • Flat upper surface or edge of an object
  • Child's toy that spins on its point
  • Upper section or leaves of fruits and vegetables
  • Winning in a sport or contest
  • verb
  • To be higher or larger than a specific value
  • To arrive at the highest point of something
  • To put a cover or layer or over something
  • To kill; murder
  • To hold the highest position on a list
  • To be more important, successful or better than
  • To beat someone or win at a game

add

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US / æd /

UK / æd /

A1
  • verb
  • To include as well
  • To put two things or numbers together, e.g. 2+2

take

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US / teɪk /

UK / tek /

A1
  • noun
  • Filming of a single scene for TV or the movies
  • verb
  • To accept something that is offered
  • To use a method of traveling, e.g. a bus or train
  • To use a camera to make (a photo)
  • To pick up something and go away with it
  • To study a subject in school
  • To attempt to pass (an exam)
  • To require a certain amount of time, money, space

clearly

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US / ˈklɪəlɪ /

UK / ˈklɪrlɪ /

A1
  • adverb
  • In a way that is easy to understand; obviously

legitimately

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US / lɪ'dʒɪtɪmətlɪ /

UK / lɪ'dʒɪtɪmətlɪ /

B2
  • adverb
  • In a lawfully recognized manner

subtract

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US / səbˈtrækt /

UK / səbˈtrækt /

B2
  • other
  • To take away a value or amount from another
  • verb
  • To take away a value or amount from another

pretty

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US / 'prɪtɪ /

UK / ˈprɪti /

A1
  • adjecitve
  • Being attractive to the eye in a simple way
  • adverb
  • Very; to a great degree

bit

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US / bɪt /

UK / bɪt /

A1
  • noun
  • Device put in a horse's mouth to control it
  • Small piece of something
  • verb
  • (E.g. of fish) to take bait and be caught

digit

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US / ˈdɪdʒɪt /

UK / ˈdɪdʒɪt /

B2
  • noun
  • Person's finger or toe
  • Written symbol of the numbers from 0 to 9

general

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US / 'dʒenrəl /

UK / ˈdʒɛnərəl /

A1
  • adjecitve
  • Widespread, normal or usual
  • noun
  • Top ranked officer in the army

hundredth

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US / ˈhʌndrədθ /

UK / ˈhʌndrɪdθ /

A1
  • noun
  • 100th

look

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US / lʊk /

UK / lʊk /

A1
  • noun
  • Person's beauty or physical attractiveness
  • Particular style of dress, clothes, or appearance
  • The way someone, something appears to be
  • Act of searching for or examining something
  • verb
  • To appear to be; seem

multiply

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US / ˈmʌltɪplaɪ /

UK / ˈmʌltəˌplaɪ /

B1
  • verb
  • To increase in number by reproducing/having babies
  • To increase something by a large quantity
  • To have increased by a large quantity
  • To calculate two numbers e.g. 2 x 4

red

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US / red /

UK / rɛd /

A1
  • adjecitve
  • Being the color of blood

decimal

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US / 'desɪml /

UK / ˈdɛsəməl /

B2
  • noun
  • Number using one equal tenth of a whole as a basis

combination

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US / ˌkɒmbɪ'neɪʃn /

UK / ˌkɑmbəˈneʃən /

B1
  • noun
  • Series of letters or numbers needed to open a lock
  • Act or result of mixing things together

much

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US / mʌtʃ /

UK / mʌtʃ /

A1
  • adjecitve
  • Very; to a high level or degree
  • adverb
  • A lot; large amount; a high degree of
  • Nearly; basically
  • On many occasions; often
  • noun
  • A large amount; a great quantity

ask

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US / ɑ:sk /

UK / æsk /

A1
  • verb
  • To say to someone that you want something

limit

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US / 'lɪmɪt /

UK / ˈlɪmɪt /

A2
  • noun
  • Point beyond which it is not possible to go
  • verb
  • To stop or prevent an increase past a point

well

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US / wel /

UK / wɛl /

A1
  • adjecitve
  • Being in a fortunate, good condition or state
  • Healthy and in good condition
  • adverb
  • In an acceptable, proper, or successful manner
  • In a complete, total, or full manner
  • A great and considerable degree
  • In a successful way, in a good or satisfactory way
  • exclamation
  • Used to begin or continue a particular statement
  • Used to show you want to start saying something
  • Used to express that you are waiting for a reply
  • You say this to change the topic of a conversation
  • Used to indicate you are making a final remark
  • noun
  • Long deep hole in the ground to get water
  • verb
  • To cause your eyes to fill with tears

since

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US / sɪns /

UK / sɪns /

A1
  • adverb
  • At a point before the present time
  • conjunction
  • For this reason; because
  • preposition
  • From the time in the past that

just

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US / dʒʌst /

UK / dʒʌst /

A1
  • adjecitve
  • Proper or appropriate; as is deserved
  • Doing or being what is right or fair
  • Legally correct; having enough evidence
  • adverb
  • Almost; nearly
  • Exactly at the time of
  • Exactly (the same as, like)

line

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US / laɪn /

UK / laɪn /

A1
  • noun
  • Border that divides two places or regions
  • Long crease in the skin, often from age
  • Mark that is long, straight and very thin
  • Row of words, letters or numbers that are written
  • Telephone connection
  • People waiting one behind the other; queue
  • Long thin wire, e.g. for electrical signal
  • verb
  • To put material along the inside of something

talk

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US / tɔ:k /

UK / tɔk /

A1
  • noun
  • Style of speaking
  • Discussion between two countries
  • Giving information in front of people; lecture
  • Saying things or ideas to someone with words
  • verb
  • To make a formal speech about something
  • To say things or ideas to someone with words

for

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US / fə(r) /

UK / fɔr,fə /

A1
  • preposition
  • Used to show the purpose, or need of something

time

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US / taɪm /

UK / taɪm /

A1
  • noun
  • Speed at which music is played; tempo
  • Point as shown on a clock, e.g. 3 p.m
  • Number of hours, minutes needed to do something
  • Occasion when something happens
  • Period or occasion that something occurred
  • Period in history or the past
  • Something measured in minutes, hours, days, etc.
  • How long an event takes; duration
  • verb
  • To check speed at which music is performed
  • To choose a specific moment to do something
  • To measure how long an event takes, e.g. a race
  • To schedule something to occur at a specific moment

why

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US / waɪ /

UK / hwaɪ, waɪ /

A1
  • adverb
  • Question word to ask for a reason
  • exclamation
  • (Used to express surprise or approval)

tower

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US / 'taʊə(r) /

UK / ˈtaʊɚ /

A2
  • noun
  • Tall, narrow building
  • Tall metal structure for broadcasting, or the view
  • verb
  • To be very good at something

imply

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US / ɪmˈplaɪ /

UK / ɪmˈplaɪ /

A2
  • verb
  • To suggest something, without saying it directly

those

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US / ðəʊz /

UK / ðoz /

A1
  • determiner
  • The people or things we are talking about
  • pronoun
  • The objects far from the speaker

situation

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US / ˌsɪtʃuˈeɪʃn /

UK / ˌsɪtʃuˈeʃən /

A1
  • noun
  • Place, position or area that something is in
  • Circumstance or condition surrounding an event
  • An unexpected problem or difficulty

difference

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US / 'dɪfrəns /

UK / ˈdɪfərəns, ˈdɪfrəns /

A1
  • noun
  • A thing or issue that people do not agree about
  • Not of the same kind; unlike other things

centimetre

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US / ˈsentɪmi:tə(r) /

UK / ˈsɛntəˌmitɚ /

A1
  • noun
  • One hundredth of a meter

point

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US / pɔɪnt /

UK / pɔɪnt /

A1
  • noun
  • An item to be discussed
  • Small spot or dot
  • Fact or detail
  • Feature of something
  • The size of the text on a page or screen
  • A certain time or stage in a process
  • Certain position in time or space
  • Idea or fact you try to convince people about
  • Measurement of scores in a game, sport
  • Sharp end of something, e.g. a pen or pin
  • verb
  • To face a certain direction, e.g. north
  • To indicate something with your finger to others

either

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US / ˈaɪðə(r) /

UK / ˈiðɚ, ˈaɪðɚ /

A1
  • adjecitve
  • One of two (used when there is a choice of two)
  • adverb
  • (After negative statements) likewise, in addition
  • conjunction
  • Used as the first of two connected things
  • determiner
  • Used as the first of two connected things
  • pronoun
  • The one or the other

here

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US / hɪə(r) /

UK / hɪr /

A1
  • adverb
  • In this place; at this location, position or time

scientific

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US / ˌsaɪənˈtɪfɪk /

UK / ˌsaɪənˈtɪfɪk /

A2
  • adjecitve
  • Concerning academic study of the physical world

tenth

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US / tenθ /

UK / tɛnθ /

A1
  • noun
  • 10th

small

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US / smɔ:l /

UK / smɔl /

A1
  • adjecitve
  • Little in size; not big
  • (Of letters) not written in capital letters
  • Being insignificant or minor
  • (Of a business) with few people or things; local
  • (Of voice) being soft and quiet
  • (Of a child) being young

quick

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US / kwɪk /

UK / kwɪk /

A1
  • adjecitve
  • Using very little time; moving far in little time
  • Learning and understanding rapidly and easily

someone

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US / ˈsʌmwʌn /

UK / ˈsʌmˌwʌn, -wən /

A1
  • pronoun
  • Person who is not known or named

reality

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US / rɪ'ælətɪ /

UK / riˈælɪti /

A2
  • noun
  • What is true, as opposed to what is imagined

exactly

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US / ɪgˈzæktli /

UK / ɪɡˈzæktli /

A1
  • adverb
  • No more and no less than; precisely

should

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US / ʃʊd /

UK / ʃʊd /

A1
  • other
  • Used to indicate what is proper or reasonable

millimetre

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US / ˈmɪlimi:tə(r) /

UK / ˈmɪlimiːtər /

B1
  • noun
  • Unit of measure, 1/1000 of a metre (symbol mm)

somehow

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US / ˈsʌmhaʊ /

UK / ˈsʌmˌhaʊ /

A1
  • adverb
  • In a way that is not known or certain

reason

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US / 'ri:zn /

UK / ˈrizən /

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  • noun
  • Ability to think about facts and form a judgment
  • Explanation for why something occurred or was done
  • verb
  • To think and make conclusions in a logical manner

plus

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US / plʌs /

UK / plʌs /

A2
  • noun
  • A benefit or advantage
  • preposition
  • In addition; add
  • In addition to; Indicates a number above
  • Having a value greater than zero

divide

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US / dɪ'vaɪd /

UK / dɪˈvaɪd /

A2
  • verb
  • To split numbers by another number, e.g. 6 / 2 = 3
  • To separate something into equal pieces

four

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US / fɔ:(r) /

UK / fɔr, for /

A1
  • number
  • 4

matter

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US / 'mætə(r) /

UK / ˈmætɚ /

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  • noun
  • Material all things are made of that fills space
  • Problem or reason for concern
  • verb
  • To be of great importance; to count

misrepresent

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US / ˌmɪsˌreprɪˈzent /

UK / ˌmɪsˌreprɪˈzent /

B2
  • verb
  • To purposely give a false impression; to deceive

once

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US / wʌns /

UK / wʌns /

A1
  • adverb
  • One time; one instance
  • At a time in the past
  • conjunction
  • When; as soon as

probably

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US / ˈprɒbəbli /

UK / ˈprɑbəbli /

A1
  • adverb
  • That is likely to happen or be true

obviously

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US / ˈɒbviəsli /

UK / ˈɑːbviəsli /

A2
  • adverb
  • In a way that is obvious/easy to see or understand

always

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US / 'ɔ:lweɪz /

UK / ˈɔlwez,-wɪz,-wiz /

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  • adverb
  • For a very long time
  • At all times; in every situation
  • For ever

guess

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US / ɡes /

UK / ɡɛs /

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  • noun
  • Answer given when you don't know if it is correct
  • verb
  • To give an answer without knowing if it is correct

many

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US / 'menɪ /

UK / ˈmɛni /

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  • determiner
  • Used to refer a large number of things

lay

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US / leɪ /

UK / le /

A2
  • adjecitve
  • Amateur; not being a trained priest
  • verb
  • To place a bet on a game outcome
  • (Of a bird, etc.) to produce eggs from its body
  • To put or set something down in a flat position
  • To set out things on (table) to prepare for a meal

will

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US / wɪl /

UK / wɪl /

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  • noun
  • Desire or choice of someone
  • Document saying who gets your money when you die
  • Strong desire to do something; determination
  • Desire to do something; strong wish to do
  • other
  • Used with verbs to express the future
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  • To leave property to someone after your death
  • To use mental effort to make something happen
  • Am (is, are) likely to do
  • To influence someone to do something
  • To make something happen by strongly wanting it

actually

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US / ˈæktʃuəli /

UK / ˈæktʃuəli /

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  • adverb
  • Used to add new (often different) information

stick

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US / stɪk /

UK / stɪk /

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  • noun
  • Long thin piece of wood from a tree
  • verb
  • To push a sharp or pointed object into something
  • To join together using glue or paste
  • To remain in one place or position for a long time

write

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US / raɪt /

UK / raɪt /

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  • verb
  • To compose letters and words on paper or a screen
  • To invent or create a computer program
  • To create a song or piece of music
  • Introduction to Video Content
  • In this video, we will be exploring addition and subtraction with significant figures in the context of decimals. We have previously learned that when multiplying or dividing numbers, the result can only have as many significant digits as the number with the fewest significant digits. For example, if we multiply 2.00 by 3.5, our answer can only have two significant digits. However, when it comes to addition and subtraction, a different rule applies. The number of decimal places becomes more important than the number of significant figures. We will go through numerical examples as well as real-world scenarios to better understand this concept. So let's dive in!Before we begin, let's address the topic of rounding in real-world examples. In the previous video, I used the example of laying down carpet and mentioned rounding up. However, it's important to note that this is specific to carpet and may not apply universally. Rounding up makes sense in the context of easily cutting away excess carpet, but it's not a general rule for all situations. Now, let's move on to addition and subtraction. When adding or subtracting numbers, the precision and number of decimal places matter more than the number of significant digits. To illustrate this, let's take the numbers 1.26 and add them together with another number. Stay tuned to find out how decimal places affect our calculations!
  • Subtitles section
  • We saw in the last video that when you multiply or you divide numbers, or I guess we should say when we multiply or divide measurements, your result can only have as many significant digits as the thing with the smallest significant digits that you ended up multiplying and dividing.
  • So just as a quick example, if I have 2.00 times, I don't know, let me, 3.5, my answer over here can only have two significant digits.
  • This has two significant digits.
  • This has three.
  • 2.00 times 3.5 is seven.
  • And we can get to one level, one, we can go one, zero to the right of the decimal because we can have two significant digits.
  • This was three, this is two.
  • We only limit it to two because that was the smallest number of significant digits we had in all of the things that we were taking the product of.
  • When we do addition and subtraction, it's a little bit different.
  • And I'll do an example first.
  • I'll just do kind of a numeric example first and then we'll think of a little bit more of a real world example.
  • And obviously, even my real world examples aren't really real world.
  • In the last video, I talked about laying down carpet.
  • And someone rightfully pointed out, hey, if you're laying down carpet, you always want to round up, just because it's easier to cut carpet away than to have to somehow glue carpet there.
  • But that's particular to carpet.
  • I was just saying a general way to think about precision and significant figures.
  • But that was particular only to maybe carpets or tiles.
  • But when you add or subtract, now the significant digits or the significant figures don't matter as much as the actual precision of the things that you're adding.
  • How many decimal places do you go?
  • So for example, if I were to add 1.26 and I were to add it to, Let's say add these two numbers up.
  • And let's say these are measurements.
  • So when you make it, this is clearly three significant digits.
  • We were able to measure to the nearest hundredth.
  • Here, this is two significant digits.
  • So three significant digits.
  • This is two significant digits.
  • We're able to measure to the nearest tenth.
  • Let me label this.
  • This is the hundredth.
  • This is the tenth.
  • When you add or subtract numbers, your answer.
  • So if we just do this, if we just add these two numbers, I get what?
  • I get 3.56.
  • The sum or the difference, whatever you take, you don't count significant figures.
  • So you don't say, hey, this can only have two significant figures.
  • What you say is, this can only be as precise as the least precise thing that I had over here.
  • The least precise thing I had over here was 2.3. It only went to the tenths place.
  • So in our answer, we can only go to the tenths place.
  • So we need to round this guy up, because we have a 6 right here.
  • So you round up.
  • So if you care about significant figures, this is going to become a 3.7. And I want to be clear.
  • This time it worked out, because this also has two significant figures.
  • This has two significant figures.
  • But this could have been, let me do another situation.
  • You could have 1.26 plus 102.3. And then you would get, obviously, you would get 103.56.
  • And in this situation, this obviously over here has four significant figures.
  • This over here has three significant figures.
  • But in our answer, we don't want to have three significant figures.
  • We want to be only as precise as the least precise thing that we added up.
  • The least precise thing, we only go one digit behind the decimal over here.
  • So we can only go to the tenths, only one digit behind the decimal there.
  • So once again, we round up to 103.6. And to see why that makes sense, let's do a little bit of an example here with actually measuring something.
  • So let's say I have a block here.
  • Let's say that I have a block.
  • Let me draw that block a little bit neater.
  • And let's say we have a pretty good meter stick.
  • And we're able to measure it to the nearest centimeter.
  • And we get it is 2.09 meters.
  • And let's say we have another block.
  • Let's say we have another block.
  • And this is the other block right over there.
  • And let's say we have even a more precise meter stick that can measure to the nearest millimeter.
  • And we get this to be 1.901 meters.
  • So we're measuring to the nearest millimeter.
  • And let's say that those measurements were done a long time ago.
  • And we don't have access to measure them anymore.
  • But someone says, how tall is it if I were to stack the blue block on top of the red block, or the orange block, or whatever color that is?
  • So how high would this height be?
  • Well, if you didn't care about significant figures or precision, you would literally just add them up.
  • You would add the 1.901 plus the 2.09.
  • So let me add those up.
  • So if you take 1.901 and add that to 2.09, you get 1 plus nothing is 1. 0 plus 9 is 9. 9 plus 0 is 9. You get the decimal point.
  • 1 plus 2 is 3. So you would get 3.991.
  • And the problem with this, the reason why this is a little bit kind of misrepresenting how precise your measurement is, is that you don't know.
  • If I told you that the tower is 3.991 meters tall, I'm implying that I somehow was able to measure the entire tower to the nearest millimeter.
  • The reality is I was only able to measure part of the tower to the nearest millimeter.
  • This part of the tower, I was only able to measure to the nearest centimeter.
  • So to make it clear that our measurement is only good to the nearest centimeter, because there's more error here than it might overwhelm whatever precision we had on the millimeters there, to make that clear,
  • We need to make this only as precise as the least precise thing that we're adding up.
  • So over here, the least precise thing was we went to the 100s.
  • So over here, we have to round to the 100s.
  • And since 1 is less than 5, we're going to round down.
  • And so we can only legitimately say, if we want to represent what we did properly, that the tower is 3.99 meters.
  • And I also want to make it clear that this doesn't just apply to when there is a decimal point.
  • If I were to tell you that, let's say that I were to measure a building, and I was only able to measure the building to the nearest 10 feet.
  • So I tell you that that building is 350 feet tall.
  • So this is the building.
  • This is a building.
  • And let's say that there's a manufacturer of radio antennas or radio towers.
  • And the manufacturer has measured their tower to the nearest foot.
  • And they say that their tower is 8 feet tall.
  • So notice, here they measured to the nearest 10 feet.
  • Here they measured to the nearest foot.
  • And actually, to make it clear, because once again, as I said, this is ambiguous.
  • It's not 100% clear how many significant figures there are.
  • Maybe it was exactly 350 feet.
  • Or maybe they just rounded to the nearest 10 feet.
  • So a better way to represent this would be to say, instead of writing it 350, a better way to write it would be 3.5 times 10 to the second feet tall.
  • And when you write it in scientific notation, it makes it very clear that there's only two significant digits here.
  • You only measured to the nearest 10 feet.
  • Other ways to represent it, you could write 350.
  • This notation is done less.
  • But sometimes the last significant digit has a line on top of it.
  • Or the last significant digit has a line below it.
  • So either of those are ways to specify it.
  • This is probably the least ambiguous.
  • But assuming that they only measured to the nearest 10 feet, and someone would ask you, how tall is the building plus the tower?
  • Well, your first reaction would just let's just add the 350 plus 8. You would get 358 feet.
  • So this is the building plus the tower is 358 feet.
  • But once again, we're misrepresenting it.
  • We're making it look like we're able to measure the combination to the nearest foot.
  • Well, we're only able to measure the tower to the nearest foot.
  • So in order to represent our measurement at the level of precision that we really did, we really have to round this to the nearest 10 feet.
  • Because that was our least precise measurement.
  • So we would really have to round this up.
  • 8 is greater than or equal to 5. So we'll round this up to 360 feet.
  • So once again, whatever is, and just to make it clear, and even this is ambiguous, maybe we put a line over it to show that that is our level of precision, that we only have two significant digits.
  • Or we could write this as 3.6 times 10 to the second, which is just 100, 3.6 times 10 to the second feet in scientific notation.
  • And this makes it very clear that we only have two significant digits here.