Divisibility

There are 74 NRICH Mathematical resources connected to Divisibility
Skeleton
problem

Skeleton

Age
11 to 14
Challenge level
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Amazing as it may seem the three fives remaining in the following `skeleton' are sufficient to reconstruct the entire long division sum.

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?

Public Key Cryptography
article

Public Key Cryptography

An introduction to coding and decoding messages and the maths behind how to secretly share information.
Multiple Surprises
problem
Favourite

Multiple Surprises

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

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.
What numbers can we make?
problem
Favourite

What numbers can we make?

Age
11 to 14
Challenge level
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Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?

Curious number
problem
Favourite

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?
Newspaper Sheets
problem

Newspaper Sheets

Age
14 to 16
Challenge level
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From only the page numbers on one sheet of newspaper, can you work out how many sheets there are altogether?
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?
Gran, how old are you?
problem

Gran, how old are you?

Age
7 to 11
Challenge level
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When Charlie asked his grandmother how old she is, he didn't get a straightforward reply! Can you work out how old she is?