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Unlike denominators: adding up to 1

You learn to add and subtract fractions that have different numbers below the line.

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How to work it out

  1. Make denominators equal before adding or subtracting.
  2. Find a number in the times tables of both denominators: the new denominator.
  3. Whatever you do to the bottom, do to the top.
  4. Add or subtract the numerators, and simplify if you can.
12=3613=2656

12 + 13

  1. Multiply the top and the bottom of 12 by 3: 36.
  2. Multiply the top and the bottom of 13 by 2: 26.
  3. Add the tops: 3 + 2 = 5.
  4. It is 56.
More examples

12 + 14

  1. Multiply the top and the bottom of 12 by 4: 48.
  2. Multiply the top and the bottom of 14 by 2: 28.
  3. Add the tops: 4 + 2 = 6, so 68.
  4. Simplify it: it is 34.
12=2414=1434

34 − 13

  1. Multiply the top and the bottom of 34 by 3: 912.
  2. Multiply the top and the bottom of 13 by 4: 412.
  3. Subtract the tops: 9 − 4 = 5.
  4. It is 512.
34=91213=412512