Divisibility

There are 75 NRICH Mathematical resources connected to Divisibility
What numbers can we make now?
problem
Favourite

What numbers can we make now?

Age
11 to 14
Challenge level
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Imagine we have four bags containing numbers from a sequence. What numbers can we make now?

Multiple Surprises
problem
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Multiple surprises

Age
11 to 16
Challenge level
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Sequences of multiples keep cropping up...
Division Rules
problem
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Division rules

Age
7 to 11
Challenge level
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This challenge encourages you to explore dividing a three-digit number by a single-digit number.
Odd Stones
problem
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Odd stones

Age
14 to 16
Challenge level
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On a "move" a stone is removed from two of the circles and placed in the third circle. Here are five of the ways that 27 stones could be distributed.
Fac-Finding
problem
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Fac-finding

Age
14 to 16
Challenge level
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Lyndon chose this as one of his favourite problems. It is accessible but needs some careful analysis of what is included and what is not. A systematic approach is really helpful.
Take Three From Five
problem
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Take three from five

Age
11 to 16
Challenge level
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Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?

Prime AP
problem
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Prime ap

Age
16 to 18
Challenge level
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What can you say about the common difference of an AP where every term is prime?
Neighbours
problem
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Neighbours

Age
7 to 11
Challenge level
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In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
LCM Sudoku
problem
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Lcm sudoku

Age
14 to 16
Challenge level
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Here is a Sudoku with a difference! Use information about lowest common multiples to help you solve it.
What an odd fact(or)
problem
Favourite

What an odd fact(or)

Age
11 to 14
Challenge level
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Can you show that 1^99 + 2^99 + 3^99 + 4^99 + 5^99 is divisible by 5?