Fractions with the same denominator: plus and minus
You learn to add and subtract fractions that have the same number below the line.
How to work it out
- Check that the number below the line is the same in both.
- Add the numbers above the line, or subtract them.
- Keep the number below the line.
- Simplify the answer if you can.
34
A worked example
14 + 24
- Both have 4 at the bottom: the pieces are equal.
- Add the tops: 1 + 2 = 3.
- It is 34.
More examples
34 − 24
- Both have 4 at the bottom.
- Subtract the tops: 3 − 2 = 1.
- It is 14.
14
78 − 38
- Both have 8 at the bottom.
- Subtract the tops: 7 − 3 = 4, so 48.
- Simplify it: 48 is 12.
48
14 + 14
- Both have 4 at the bottom.
- Add the tops: 1 + 1 = 2, so 24.
- Simplify it: 24 is 12.
24
Watch out
You add the numbers below the line too: 14 + 24 becomes 38.
The pieces stay equal. Leave the number below the line.
You take away the numbers below the line too: 34 − 14 becomes 20.
The number below the line stays: 24.
Tips
- Simplify the answer afterwards if you can: 24 is 12.
- If the answer is more than a whole, like 34 + 34 = 64, write it as 1 24.
Why it works
When the numbers below the line are the same, the pieces are equal. Then you just add or take away pieces: 1 quarter and 2 quarters together are 3 quarters, and 3 quarters minus 1 quarter is 2 quarters. The size of the piece does not change, so the number below the line stays the same.