# If subtracting is your aim

the bottom numbers must be the same

And to put all the fractions with the same bottom number you must:

Multiply the top and bottom of each fraction by
the other fraction's bottom number

Note: There are many ways to subtract fractions but with Mammoth Memory, we propose this one method that suits every subtraction of a fraction. That way you only have one rhyming slogan to remember.

Example 1

5/9-1/9=(5-1)/9=4/9

In this example, the bottom numbers (denominators) are the same.

Example 2

5/6-3/8

Make the bottom denominator the same for both so multiply the top and bottom of each fraction by the other fraction's denominator.

5/6\times8/8-3/8\times6/6

NOTE:

6/6\ or8/8=1

When multiplying by 1 it does not alter the fraction.

Therefore

5/6\times8/8=(5\times8)/(6times8)=40/48

and

3/8\times6/6=(3\times6)/(8times6)=18/48

So subtract fractions

40/48\-18/48=(40\-18)/(48)=22/48

Now just make 22/48 simpler

22/48=11/24

Example 3

Work out  3/4-1/6

Make the bottom denominator the same for both so multiply the top and bottom of each fraction by the other fraction's denominator.

3/4\times6/6-1/6\times4/4

NOTE:

6/6\ or4/4=1

When multiplying by 1 it does not alter the fraction.

Therefore

3/4\times6/6=(3\times6)/(4times6)=18/24

and

1/6\times4/4=(1\times4)/(6times4)=4/24

subtract fractions

18/24\-4/24=(18\-4)/(24)=14/24

Now just make 14/24 simpler

14/24=7/12