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Subtracting fractions with like denominators
When two fractions have the same denominator, the pieces are the same size. So you just subtract the numerators (the tops) and keep the denominator. 7/8 − 3/8 = 4/8, which simplifies to 1/2.
The most common mistake is subtracting the bottoms too, which would give 4/0. Ask your child: "Did the size of the pieces change?" It didn't, so the bottom stays.
Worked examples
- 5/6 − 1/6 = 4/6 = 2/3.
- From a whole: 1 − 3/5 = 2/5, because one whole is 5/5.
- Mixed numbers: 2 3/4 − 1 1/4 = 1 2/4, which is the same as 1 1/2.
6 practice questions (answers simplified)
- 4/5 − 1/5 = ?
- 7/9 − 4/9 = ?
- 9/10 − 3/10 = ?
- 5/8 − 1/8 = ?
- 11/12 − 5/12 = ?
- 6/7 − 6/7 = ?
Show answers
- 4/5 − 1/5 = 3/5
- 7/9 − 4/9 = 1/3
- 9/10 − 3/10 = 3/5
- 5/8 − 1/8 = 1/2
- 11/12 − 5/12 = 1/2
- 6/7 − 6/7 = 0
Tips for parents
- Say it in words: "seven eighths take away three eighths is four eighths."
- Draw a bar split into the denominator's number of parts and cross out pieces.
- Simplify the answer when you can.