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Unit 7: Numeracy skills

Fractions

Adding Fractions: 2

Sometimes the denominators are not multiples of each other, for example:

1 + 2    
-   -
4   3    

In this case we can make 12 the common denominator using

1 = 1 x 3 =   3   2 = 2 x 4 =   8
-   - -   ------ -   -   -   -----
4   3   3   1 2   3   3   4   1 2

We can then add these two fractions directly:

1 + 2 =   3 +   8 = 3 + 8 = 1 1
-   - ---   ----   ----------   -----
4   3   1 2   1 2     1 2   1 2

Another example:

2 + 1 = ?
-   -
5   6    

2 = 2 x 6 = 1 2   1 = 1 x 5 =   5
-   - -   ------ -   -   -   -----
5   5   6   3 0   6   6   5   3 0

2 + 1 = 1 2 +   5 = 1 2 + 5 = 1 7
-   - ---   ----   ------------   ----
5   6   3 0   3 0     3 0     3 0

Creative Commons License
SMILE - Numeracy skills by Tom Frank, Eric Williams and Clare Wright, University of Birmingham Careers Centre adapted by Marion Kelt Glasgow Caledonian University is licensed under a Creative Commons Attribution 3.0 Unported License.