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Subtracting fractions with like denominators

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Subtracting Fractions with Like Denominators

To subtract fractions with like denominators, subtract the numerators and keep the common denominator the same, then simplify the result if possible. For example, 5/8 minus 2/8 equals 3/8. Learn the steps and see worked examples, including when to reduce the answer.

Subtracting fractions with like denominators

When two fractions have the same (like) denominator, subtracting them is simple: subtract the numerators and keep the denominator the same. The denominator tells you the size of the pieces, and since both fractions use the same size pieces, only the count changes. If you are still getting comfortable with fractions, review what fractions are first.

Subtracting fractions with like denominators A bar of eighths with five parts shaded, minus a bar with two parts shaded, equals a bar with three parts shaded. Five eighths minus two eighths equals three eighths: subtract the numerators and keep the denominator. 5/8 − 2/8 = 3/8 Subtract the numerators; keep the denominator.
5/8 − 2/8 = 3/8: subtract the numerators, keep the denominator.

To work out a difference such as 5/8 − 2/8: subtract the numerators (5 − 2 = 3), keep the denominator (8), which gives 3/8. Then simplify the result if you can. For 6/8 − 2/8 = 4/8, both numbers share a factor of 4, so 4/8 reduces to 1/2.

  • 7/10 − 3/10 = 4/10, which simplifies to 2/5.
  • 9/12 − 5/12 = 4/12, which simplifies to 1/3.
  • 3/4 − 1/4 = 2/4 = 1/2.

Subtracting works exactly like adding fractions with like denominators, just with a minus instead of a plus.

This shortcut only works when the denominators match. If they are different, you first rewrite the fractions with a common denominator — see subtracting fractions with unlike denominators.

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