Factors and multiples

There are 243 NRICH Mathematical resources connected to Factors and multiples
Curious number
problem

Curious number

Age
7 to 11
Challenge level
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Can you order the digits from 1-3 to make a number which is divisible by 3 so when the last digit is removed it becomes a 2-figure number divisible by 2, and so on?
Ip Dip
problem

Ip Dip

Age
5 to 11
Challenge level
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"Ip dip sky blue! Who's 'it'? It's you!" Where would you position yourself so that you are 'it' if there are two players? Three players ...?
Rolling Along the Trail
problem

Rolling Along the Trail

Age
11 to 14
Challenge level
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What could be the scores from five throws of this dice?
Indivisible
problem

Indivisible

Age
14 to 16
Challenge level
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Each time a class lines up in different sized groups, a different number of people are left over. How large can the class be?
Sticky Fingers
problem

Sticky Fingers

Age
14 to 16
Challenge level
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Ruth wants to puts stickers on the cuboid she has made from little cubes. Will she have any stickers left over?
Adjacent Factors
problem

Adjacent Factors

Age
11 to 14
Challenge level
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Two numbers can be placed adjacent if one of them divides the other. Using only $1,...,10$, can you write the longest such list?
Factor List
problem

Factor List

Age
14 to 16
Challenge level
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Tina has chosen a number and has noticed something about its factors. What number could she have chosen? Are there multiple possibilities?
Product 100
problem

Product 100

Age
11 to 14
Challenge level
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The product of four different positive integers is 100. What is the sum of these four integers?
Light the Lights
problem

Light the Lights

Age
5 to 7
Challenge level
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Investigate which numbers make these lights come on. What is the smallest number you can find that lights up all the lights?
Light the Lights Again
problem

Light the Lights Again

Age
7 to 11
Challenge level
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Each light in this interactivity turns on according to a rule. What happens when you enter different numbers? Can you find the smallest number that lights up all four lights?