GCSE maths revision


Finding a fraction of an amount


When finding a fraction of an amount, the key rule to remember is to divide the amount by the denominator and multiply your answer by the numerator.

If asked to increase or decrease an amount by a fraction make sure you add or subtract from the original amount at the end of the question!

Example questions involving fractions of amounts

Example 1 - Finding a fraction of an amount

Find \(\frac{2}{5}\) of £35.

First find \(\frac{1}{5}\) by dividing £35 by 5 to get £7.

Now to find \(\frac{2}{5}\), multiply by 2 to get £7 × 2 = £14.

Example 2 - Increasing or decreasing an amount by a fraction

Increase £240 by \(\frac{1}{6}\).

£240 ÷ 6 = £40. So \(\frac{1}{6}\) of £240 is £40.

Since we want to increase the amount by \(\frac{1}{6}\) we add this on to the original amount of £240. So £240 + £40 = £280.

Example 3 - Multiplying a whole number by a fraction

Calculate \(\frac{3}{7}\) × 140.

Multiplying a fraction by a whole number is exactly the same as finding a fraction of an amount. In fact, when dealing with fractions the '×' symbol and the word 'of' usually mean the same thing.

So, 140 ÷ 7 = 20 and then 20 × 3 = 60.

Test yourself!

Now try these worksheets to practise your skills.