The first of these two free maths worksheets tries to get across the idea that multiplying a number by ten and then multiplying by ten again is the same as multiplying by 100. To multiply by 100 we simply move each digit of the number two places to the left.
(A decimal point will remain static – it does not move as it separates the units from the tenths!)
In the same way, to divide by ten and then divide by ten again is the same as dividing by 100. To divide by 100 we move each digit two places to the right. This may mean inserting a decimal point where necessary.
For example 9 divided by 10 is 0.9 (Remember 9 can be written as 9.0)
0.9 divided by 10 is 0.09
Hence 9 divided by 100 is 0.09.
The second sheet looks at the questions, “How many times larger or how many times smaller?”
eg How many times smaller is 2.5 than 25.
Put another way, “What do you have to multiply 2.5 by to make 25?” The answer is 10 because each digit will be moved one place to the left.
We have probably reached a point here where some children will be struggling, especially if they were taught to ‘add a nought’ earlier in their maths. This idea of moving digits to the left and right is fundamental to understanding the value of numbers – absolutely fundamental!!
Free Y5 maths worksheets: Multiply and divide by 10 and 100 (pg 1)
Free Y5 maths worksheets: Multiply and divide by 10 and 100 (pg 2)