Worked example 1
3/4 of 28
- Divide by the bottom: 28 ÷ 4 = 7.
- Times by the top: 7 × 3 = 21.
Answer: 21
Maths · Intermediate
Finding fractions of amounts
Finding a fraction of an amount means working out, for example, 3/4 of 20 sweets or 2/5 of £45. It is used in recipes, discounts and sharing.
- 1Learn it
- 2See it worked
- 3Try it online
- 4Print it
- 5Check your answer
Before you start
Who it's for and what to know first
Division and multiplication facts; knowing that the bottom number (denominator) says how many equal parts.
Learn it
How it works
- The denominator (bottom) tells you how many equal groups to split into. The numerator (top) tells you how many of those groups you want.
- Rule: divide by the bottom, times by the top.
- For unit fractions (numerator 1), just divide: 1/5 of 30 = 30 ÷ 5 = 6.
- Check it makes sense: less than a whole fraction must give less than the amount.
Worked example 2
2/5 of £45
- £45 ÷ 5 = £9.
- £9 × 2 = £18.
Answer: £18
Try it online · print it · check it
Practice questions
Tips
Common mistakes
- Dividing by the top number instead of the bottom.
- Stopping after the divide step when the numerator is not 1.
Last reviewed: 25 September 2026