Multiplying and dividing fractions · Usually met around P5
Fractions of an amount
Divide by the bottom, times the top.
How to do it
Method
Divide by the bottom, times the top
34 of 24: 24 ÷ 4 = 6, 6 × 3 = 18
Another way
Fraction multiplication
24 × 34 = 724 = 18
In full
34 of 24: the denominator tells you how many equal parts there are, and the numerator tells you how many of them to take. Divide by the denominator to get one part: 24 ÷ 4 = 6. Then multiply by the numerator: 6 × 3 = 18. You can also write it as a fraction multiplication: 24 × 34 = 724 = 18 (or cancel first). Dividing first keeps the numbers small, so it's quicker in your head.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
13 of 18
Show the answer and working
Answer: 13 of 18 = 6
13 of 18: divide by the denominator for one part, 18 ÷ 3 = 6, then multiply by the numerator, 6 × 1 = 6
Example 2
14 of 28
Show the answer and working
Answer: 14 of 28 = 7
14 of 28: divide by the denominator for one part, 28 ÷ 4 = 7, then multiply by the numerator, 7 × 1 = 7
Example 3
14 of 20
Show the answer and working
Answer: 14 of 20 = 5
14 of 20: divide by the denominator for one part, 20 ÷ 4 = 5, then multiply by the numerator, 5 × 1 = 5
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