Keep the denominator the same.
Top tip: 28 simplifies to 14.
Learn the 3-Step Method
1Check the denominators.
Are the denominators the same?
✕ Different → You need a different method
2Subtract the numerators.
Subtract the top numbers.
3Keep the denominator.
Write the denominator once, the same as before.
Worked Example
Subtract these fractions: 78 − 28
Watch Out! Common Mistakes
Wrong! The denominator stays the same: 58.
Wrong! Only subtract the top numbers. You can never have 0 as a denominator.
Wrong! Don’t forget the denominator! The answer is 58, not 5.
⬇ Cheat Sheet
- Check the denominators are the same.
- Subtract the numerators.
- Keep the denominator the same.
- Simplify if you can.
Top number changes. Bottom number stays the same.
📖 Continue Your Journey
Quick summary
- Check the denominators are the same before you subtract.
- Subtract only the numerators: 7/8 − 2/8 = 5/8.
- The denominator stays the same — and can never be 0.
- Simplify the answer when you can: 5/8 − 3/8 = 2/8 = 1/4.
Frequently asked questions
How do you subtract fractions with the same denominator?
Subtract the numerators and keep the denominator the same. For example, 7/8 − 2/8 = 5/8.
Why does the denominator stay the same when subtracting?
The denominator tells you the size of the pieces. Taking pieces away doesn't change how big each piece is — only how many you have left.
Should the answer be simplified?
Yes, when possible. For example 5/8 − 3/8 = 2/8, which simplifies to 1/4. Examiners expect answers in their simplest form.
What about subtracting fractions with different denominators?
Make the denominators the same first using equivalent fractions — exactly as in our Adding Fractions (Different Denominator) lesson — then subtract the numerators.
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