fractionsDecimals · Year 6 · AC9M6N05

Adding unlike fractions

You can only add fractions when the pieces are the same size — that is, when the denominators match. For 1/2 + 1/3, rename both as sixths: 1/2 = 3/6 and 1/3 = 2/6. Now the pieces match, so add the numerators: 3/6 + 2/6 = 5/6. You never add the denominators. Multiplying the two denominators gives a common denominator, but remember to scale each numerator by the same factor you used on its denominator. Finish by writing the answer in simplest form.

Sample questions

2/3 + 1/2 = ? (Give your answer as a fraction in simplest form.)

  1. Common denominator 3 × 2 = 6: 2/3 = 4/6, 1/2 = 3/6.
  2. Add the numerators: 4/6 + 3/6 = 7/6.
  3. So 2/3 + 1/2 = 7/6.

Answer: 7/6

1/2 + 3/4 = ? (Give your answer as a fraction in simplest form.)

  1. Common denominator 2 × 4 = 8: 1/2 = 4/8, 3/4 = 6/8.
  2. Add the numerators: 4/8 + 6/8 = 10/8.
  3. So 1/2 + 3/4 = 5/4.

Answer: 5/4

3/4 + 1/2 = ? (Give your answer as a fraction in simplest form.)

  1. Common denominator 4 × 2 = 8: 3/4 = 6/8, 1/2 = 4/8.
  2. Add the numerators: 6/8 + 4/8 = 10/8.
  3. So 3/4 + 1/2 = 5/4.

Answer: 5/4

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