Multiplying the numerator and denominator by the same number makes an equivalent fraction: 3/4 = 6/8 = 9/12. Dividing both by the same number also works, and makes the fraction simpler.
A fraction is in its simplest form when no number except 1 divides both the top and the bottom. To simplify 12/18, divide both by 6, the biggest common factor, to get 2/3.
Worked example
Write 15/20 in its simplest form.
- 5 divides both 15 and 20.
- 15 ÷ 5 = 3 and 20 ÷ 5 = 4.
Answer:3/4
Key words
- equivalent fractions
- fractions with the same value
- simplest form
- the smallest numbers possible
- common factor
- a number that divides both
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Common Core-referenced: 4.NF.A.1