Fractions of Amounts (Cambridge (CIE) IGCSE Maths) : Revision Note

Fractions of Amounts

How do I find a fraction of an amount?

  • Method 1
    Divide by the denominator and multiply by the numerator

    • To find 1 third of 90, divide it by 3

      • 90 divided by 3 equals 30

    • To find 2 over 5 of 60, divide it by 5 then multiply it by 2

      • 60 divided by 5 equals 12, then 12 cross times 2 equals 24

  • Method 2
    Change the fraction into a decimal, then multiply

    • To find 1 fourth of 16, turn 1 fourth into 0.25 then multiply

      •  0.25 cross times 16 equals 4

    • To find 9 over 10 of 15, turn 9 over 10 into 0.9 then multiply

      •  0.9 cross times 15 equals 13.5

  • Method 3
    Write both numbers as fractions and multiply two fractions together

    • To find 2 over 3 of 60, write 60 as 60 over 1

      • work out 2 over 3 cross times 60 over 1 equals 120 over 3 equals 40

    • To find 5 over 6 of 8 over 3

      • work out 5 over 6 cross times 8 over 3 equals 40 over 18 equals 20 over 9

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Naomi C

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Naomi graduated from Durham University in 2007 with a Masters degree in Civil Engineering. She has taught Mathematics in the UK, Malaysia and Switzerland covering GCSE, IGCSE, A-Level and IB. She particularly enjoys applying Mathematics to real life and endeavours to bring creativity to the content she creates.

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