NumberKS3 / GCSE

Reverse fractions of an amount - calculation

Find the whole amount when a fraction of it is known using a short calculation.

  • The denominator tells you how many equal parts make the whole.
  • Divide the known amount by the numerator to find one part.
  • Multiply one part by the denominator to find the whole.

Example 1

Find one part

of an amount is 24. Find the whole.

Divide to find one part, then multiply

Example 2

Use the same method

of an amount is 18. Find the whole.

Divide to find one part, then multiply

Remember
For a reverse fraction, the known amount covers the numerator’s number of parts.

Your turn

Question 1

of an amount is 16. Find the whole amount.

Check answer
Question 2

of an amount is 39. Find the whole amount.

Check answer
Question 3

of an amount is 36. Find the whole amount.

Check answer
Question 4

of an amount is 45. Find the whole amount.

Check answer
Question 5

of an amount is 84. Find the whole amount.

Check answer
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