Guide
How to Find a Fraction of a Number
Finding a fraction 'of' a number is one of the most useful fraction skills in real life — and it's just divide then multiply.
Finding a fraction 'of' a number is one of the most useful fraction skills in real life — and it's just divide then multiply.
What 'of' means
In maths, the word 'of' means multiply. So '1/3 of 12' means 1/3 x 12. Finding a fraction of a number is really just multiplying.
The quick method: divide then multiply
Divide the number by the denominator, then multiply by the numerator. For 3/4 of 20: divide 20 by 4 to get 5, then multiply by 3 to get 15. So 3/4 of 20 is 15.
Worked example: 1/3 of 12
Divide 12 by the denominator 3 to get 4. Multiply by the numerator 1 to get 4. So 1/3 of 12 is 4.
Why it works
Dividing by the denominator finds the size of one equal part; multiplying by the numerator counts how many of those parts you want.
Related tools & guides
Frequently asked
How do you find a fraction of a number?
Divide the number by the denominator, then multiply by the numerator. For 1/3 of 12: 12 ÷ 3 = 4, then 4 x 1 = 4.
What is 3/4 of 20?
Divide 20 by 4 to get 5, then multiply by 3 to get 15. So 3/4 of 20 is 15.
Does 'of' mean multiply in fractions?
Yes. 'A fraction of a number' means that fraction multiplied by the number.