# Maths KS1 / KS2: How to use mental methods to multiply

Mr and Mrs Sharma can’t work out how many sausages to buy for Charlie’s birthday party.

They are trying to count it out using chocolate buttons, but they are getting in a right mess.

This sounds like a job for Multiplication Boy!

Multiplication Boy comes to the rescue, but loses his trusty number line on route.

Can he find another way to work out the answer? What if he uses the commutative law of multiplication and facts he already knows?

And will Mrs Sharma have any chocolate button left by the end of it all?

This clip is from the series A World Without Maths.

### Teacher Notes

Children might explore multiplications problems where the answers are just outside their current knowledge of the times tables.

For example, you might set out a small pile of toys and a set of party bags and try this problem: ‘Mr and Mrs Sharma really need some help planning the rest of Charlie’s party!_

There are 11 children coming to the party. They want to put two toys in each party bag. What is the calculation we need to do? How many toys will they need?’

To explore the commutative law you might ask: ‘Does it matter which way around the numbers go before the equals sign? Is 11 x 2 the same as 2 x 11? ‘ For those children who are confident you could ask ‘How can you prove this to me?’

Some children might use the objects or pictures to help them. Others may be ready to use known facts and addition to solve the problems.

### Curriculum Notes

This clip will be relevant for teaching Maths at KS1 and KS2 in England and Wales, and First and Second Level in Scotland.