# Why do numbers move to the left when multiplied by 10?

Discussion in 'Primary' started by donna1107, Jan 15, 2011.

1. ### donna1107

How can i explain this to children? When i say its because there are 10 lots more, they just stare at me!!! Ive got low ability yr 5/6

2. ### harsh-but-fairStar commenter

The extra nought weighs more than the one and tips the balance to the left...

3. ### donna1107

u couldnt explain it like that because their arent any extra naughts, because naughts are place holders, they're always there! i need a way of explaining that the numbers move to the left

4. ### carriecat10Established commenter Community helper

Have you thought of using some structured base 10 apparatus to demonstrate what happens to numbers when you multiply by 10? The children need to understand what is happening to the original number and have an image for this.

If you have a visualiser this would enable them to see how you are manipulating the resources and, is possible, do it themselves. Recording the numbers as they are multiplied by 10 will support their thinking too.

Rather than doing this as a whole class activity it may be easier in a guided group so you can prompt with appropriate questions and it will be clearer to you who does understand and who needs further support.
Carrie

5. ### Lara mfl 05Star commenter

Like carriecat I'd definietely want to demnstrate this visually, using either blocks or Dienes apparatus swapping 10 single for 1 ten & then asking then how we show there are 10 even though it comes as 1 block. I'd laminate some Tens / Units cards & get children to use them with the blocks .

6. ### shalteir

As above, with apparatus, but when ready also take it each step of the way without the apparatus, eg 14 x 10; 4 units multiplied by 10 is 40. We group 40 units into 4 tens; 1 ten x 10 = 10 tens which is one hundred. There will be 1 in the hundreds column, 4 in the tens column, and to show there are no units, put 0 in the units column.