fractionsDecimals · Year 5 · AC9M5N03
Comparing unlike fractions
To compare fractions with different denominators, you cannot just look at the top or the bottom on its own. A bigger denominator means the pieces are smaller, so 1/5 is less than 1/3. The safe method is to rename both fractions with a common denominator, then compare the numerators. For 2/3 and 3/5, use fifteenths: 2/3 = 10/15 and 3/5 = 9/15. Now 10/15 is larger, so 2/3 is larger. Multiplying the two denominators together always gives a common denominator you can use.
Sample questions
Which is larger, 3/4 or 1/5? (Type the larger fraction.)
- Rename to a common denominator of 4 × 5 = 20.
- 3/4 = 15/20 and 1/5 = 4/20.
- 15 > 4, so 3/4 is larger.
Answer: 3/4
Which is larger, 3/4 or 2/5? (Type the larger fraction.)
- Rename to a common denominator of 4 × 5 = 20.
- 3/4 = 15/20 and 2/5 = 8/20.
- 15 > 8, so 3/4 is larger.
Answer: 3/4
Which is larger, 1/2 or 1/3? (Type the larger fraction.)
- Rename to a common denominator of 2 × 3 = 6.
- 1/2 = 3/6 and 1/3 = 2/6.
- 3 > 2, so 1/2 is larger.
Answer: 1/2