Addition and subtraction

The Scot, John Napier, invented these strips about 400 years ago to help calculate multiplication and division. Can you work out how to use Napier's bones to find the answer to these multiplications?

Without doing lots of calculations, can you decide which of these number sentences are true? How do you know?

Max and Bryony both have a box of sweets. What do you know about the number of sweets they each have?

Find the values of the nine letters in the sum: FOOT + BALL = GAME

Investigate the different ways that fifteen schools could have given money in a charity fundraiser.

Throughout these challenges, the touching faces of any adjacent dice must have the same number. Can you find a way of making the total on the top come to each number from 11 to 18 inclusive?

When I fold a 0-20 number line, I end up with 'stacks' of numbers on top of each other. These challenges involve varying the length of the number line and investigating the 'stack totals'.

Watch this animation. What do you notice? What happens when you try more or fewer cubes in a bundle?