We have been doing multiplying and dividing by 10 and 100 and observing the effect. We saw that when you multiply by 10, for example 9 times 10 = 90, a zero goes to the units column and the 9 goes to the tens column. We saw when you divide by 10, for example
90 divided by 10 = 9, the zero disappears and the 9 goes to the units column.

We saw when you divide by 100, for example 900 divided by 100 = 9, two zeros disappear and the 9 goes to the units column. We saw when you multiply by 100, for example 9 times 100 = 900, 2 zeros
go to the units and the tens columns and the 9 goes to the hundreds column.

By Farshed

Check out the BBC website sometime. It has excellent interactive maths activities suitable for 4-11 year old kids.Click on the different options to try them out.
http://www.bbc.co.uk/schools/4_11/numeracy.shtml