Year 5

We are revisiting this concept.
We can now confidently multiply or divide whole numbers and decimal numbers by 10, 100 or 1000

Year 5 Unit 11

What we are learning:

•  We are revisiting this issue as it is so important.
• Although it is tempting to say ‘you just add a zero’, this does not promote understanding of the mathematics. Your child needs to know what is happening to the size of the numbers. Also, adding a zero will only work when multiplying whole numbers, it does not work for decimals i.e. 2.5 x 10 is 25 not 2.50.
• Similarly, you may have heard the phrase ‘move the decimal point’, however, the decimal point does not move, the digits (numbers) do.
• Your child also needs to understand that we use zero as a ‘place holder’ e.g.
• Children can get confused by which way the digits ‘move’. Encouraging them to think about what is happening to the size of the number will help with this.

ACTIVITY 1: HIDDEN CALCULATOR GAME, MULTIPLYING BY 10, 100,1000

Activities you can do at home:

Play the ‘Secret Calculator’ Game. A game for 2 players.
You will need: a calculator
How to play:
1. Player 1 enters a number into calculator and passes to player 2.
2. Player 2 has to secretly multiply or divide the number by 10, 100 or
1000 before passing back to player 1.

Player 1 has to work out what player 2 entered into the calculator and say what happened to the number. E.g. ‘you pressed ÷ 100 which made the number 100 times smaller’

Good questions to ask:

What has happened to the number you entered into the calculator – has it got bigger or smaller?
How many times has it got bigger or smaller by?
What did I multiply or divide your number by?

If your child:

Can write down the answers to these multiplications and divisions quickly
Ask them to tell you the answer without writing it down – this is even more difficult as they have to visualise the answers!