
Unit 7: Numeracy skills
Fractions
Adding Fractions
When the denominators (the bottom lines) are all the same, you simply add the top line (numerators)
2 | + | 3 | = | 5 | 5 | + | 3 | = | 5+3 | = | 8 | |
- | - | - | - | - | ----- | - | ||||||
6 | 6 | 6 | 9 | 9 | 9 | 9 |
Remember to cancel down if necessary.
When the denominators are different, we need to change the fractions so that the denominators are the same then we can add the top line as above. Suppose we want to calculate:
1 | + | 1 | ||
- | - | |||
2 | 4 |
From the cancelling down process we know that:
1 | = | 1 | x | 2 | = | 2 |
- | ------ | - | ||||
2 | 2 | x | 2 | 4 |
The denominators of both fractions are now the same so we can calculate
1 | + | 1 | = | 2 | + | 1 | = | 3 | ||||||||||
- | -- | - | - | -- | ||||||||||||||
2 | 4 | 4 | 4 | 4 |
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.