Factors and multiples

problem
Shifting times tables

Age

11 to 14

Challenge level

Can you find a way to identify times tables after they have been shifted up or down?
problem
How much can we spend?

Age

11 to 14

Challenge level

A country has decided to have just two different coins, 3z and 5z coins. Which totals can be made? Is there a largest total that cannot be made? How do you know?
problem
Multiples Sudoku

Age

11 to 14

Challenge level

Each clue in this Sudoku is the product of the two numbers in adjacent cells.
problem
Power mad!

Age

11 to 14

Challenge level

Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
problem
LCM Sudoku II

Age

11 to 18

Challenge level

You are given the Lowest Common Multiples of sets of digits. Find the digits and then solve the Sudoku.
problem
Venn diagrams

Age

5 to 11

Challenge level

How will you complete these interactive Venn diagrams?
problem
Trailing zeros

Age

11 to 14

Challenge level

How many zeros does 50! have at the end?
problem
Star product Sudoku

Age

11 to 16

Challenge level

The puzzle can be solved by finding the values of the unknown digits (all indicated by asterisks) in the squares of the $9\times9$ grid.
problem
Tiling

Age

7 to 11

Challenge level

An investigation that gives you the opportunity to make and justify predictions.
problem
LCM Sudoku

Age

14 to 16

Challenge level

Here is a Sudoku with a difference! Use information about lowest common multiples to help you solve it.