Divisibility

problem
Skeleton

Age

11 to 14

Challenge level

Amazing as it may seem the three fives remaining in the following `skeleton' are sufficient to reconstruct the entire long division sum.
problem
What numbers can we make now?

Age

11 to 14

Challenge level

Imagine we have four bags containing numbers from a sequence. What numbers can we make now?
article
Public key cryptography

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

Age

11 to 16

Challenge level

Sequences of multiples keep cropping up...
problem
Division rules

Age

7 to 11

Challenge level

This challenge encourages you to explore dividing a three-digit number by a single-digit number.
problem
What numbers can we make?

Age

11 to 14

Challenge level

Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
problem
Curious number

Age

7 to 11

Challenge level

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?
problem
Newspaper sheets

Age

14 to 16

Challenge level

From only the page numbers on one sheet of newspaper, can you work out how many sheets there are altogether?
problem
Indivisible

Age

14 to 16

Challenge level

Each time a class lines up in different sized groups, a different number of people are left over. How large can the class be?
problem
Gran, how old are you?

Age

7 to 11

Challenge level

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