Maths-Fractions etc.

How do we find  of 20?

Method 1 is to find  of 20, then multiply by 3.

 of 20 is  .

We need  of 20, so we multiply 4 by 3.

 of  .

Method 2 is to multiply  by 20.

•              This is how you make/get equivalent fractions.

Sometimes you can divide the top and bottom of a fraction by the same number. This is called cancelling down. It is also called simplifying the fraction. You often have to write a fraction in its simplest terms. This means that you have to cancel it down until it cannot be canceled down any more.

Write this fraction in its simplest form: 12/16

Divide by 4: 12/16 = 3/4

You could do this in two stages:

Divding the top and bottom by 2, to get 6/8

Then dividing the top and bottom by 2 again, to get 3/4

12/16 = 6/8 = 3/4.

Imagine that there are 10 questions in a test and you get 7 of them correct. You would say that you got  .

7 as a fraction of 10 is  .

In the same way, 4 as a fraction of 12 is  or  and 20 as a fraction of 48 is  or  .

Be careful with the units.

For example,  as a fraction of  is not  , but

 (  ) and  as a fraction of  is

  .