Factors and multiples

There are 252 NRICH Mathematical resources connected to Factors and multiples
Skip Counting
problem

Skip counting

Age
5 to 7
Challenge level
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Find the squares that Froggie skips onto to get to the pumpkin patch. She starts on 3 and finishes on 30, but she lands only on a square that has a number 3 more than the square she skips from.
Two Much
problem

Two much

Age
11 to 14
Challenge level
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Explain why the arithmetic sequence 1, 14, 27, 40, ... contains many terms of the form 222...2 where only the digit 2 appears.
Power Crazy
problem

Power crazy

Age
11 to 14
Challenge level
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What can you say about the values of n that make $7^n + 3^n$ a multiple of 10? Are there other pairs of integers between 1 and 10 which have similar properties?
Just Repeat
problem

Just repeat

Age
11 to 14
Challenge level
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Think of any three-digit number. Repeat the digits. The 6-digit number that you end up with is divisible by 91. Is this a coincidence?
Number Tracks
problem

Number tracks

Age
7 to 11
Challenge level
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Ben's class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?
Factor Trio
problem

Factor trio

Age
11 to 14
Challenge level
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Which of the numbers shown is the product of exactly 3 distinct prime factors?
Sorting Numbers
problem

Sorting numbers

Age
5 to 7
Challenge level
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Can you sort numbers into sets? Can you give each set a name?
Which numbers? (1)
problem

Which numbers? (1)

Age
7 to 11
Challenge level
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I am thinking of three sets of numbers less than 101. They are the red set, the green set and the blue set. Can you find all the numbers in the sets from these clues?
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?
How old are the children?
problem

How old are the children?

Age
11 to 14
Challenge level
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A student in a maths class was trying to get some information from her teacher. She was given some clues and then the teacher ended by saying, "Well, how old are they?"