Adding and subtracting fractions

You can only add fractions when the bottom numbers (denominators) match. Make them match first, then add the tops.

Key facts

  • Find a common denominator: a number both bottoms go into.
  • Whatever you multiply the bottom by, multiply the top by too.
  • Add the tops, keep the bottom, then simplify.

Worked examples

Example 1

Work out 2/3 + 1/4.

  1. 3 and 4 both go into 12. 2/3 = 8/12, 1/4 = 3/12
  2. Add the tops. 8/12 + 3/12 = 11/12

Answer: 11/12

Questions about adding and subtracting fractions