Year 6 Arithmetic (SATs): Mixed numbers and improper fractions
Part of the Year 6 Arithmetic (SATs) fractions chapter. Chapter overview · whole chapter on one page
Mixed numbers and improper fractions
Rule
A mixed number has a whole number and a fraction, such as 2 3/4. An improper fraction has a top number that is bigger than its bottom number, such as 11/4.
To change a mixed number to an improper fraction: multiply the whole number by the bottom, add the top, and keep the bottom. To change back, divide the top by the bottom.
Key ideas
- 2 3/4 = 11/4, because 2 × 4 + 3 = 11.
- 17/5 = 3 2/5, because 17 ÷ 5 = 3 remainder 2.
- An improper fraction has a top number bigger than its bottom number.
Method. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 4 parts, so 2 wholes have 2 × 4 parts.2 × 4 = 8
- Add the top number. Add the 3 parts that are left over.8 + 3 = 11
- Keep the same bottom number. The size of each part does not change.11/4
- Write the answer. 11/4
Check. 11/4 = 2 3/4, because 4 × 2 = 8 and 8 + 3 = 11. ✓
Method. Divide the top by the bottom: the whole number and the remainder make the mixed number.
- Divide the top number by the bottom number. 17 ÷ 5 = 3 with 2 left over.17 ÷ 5 = 3 r 2
- Write the answer as a mixed number. The whole number is 3, and the 2 left over goes over 5.3 2/5
- Write the answer. 3 2/5
Check. 3 × 5 + 2 = 17. ✓
Watch out. The remainder goes on top of the same bottom: 2/5, not 2/3.
Method. Change the mixed number to an improper fraction, then compare.
- The bottom numbers are the same. So compare the top numbers.7/3 and 7/3
- Compare the top numbers. 7 and 7 tell us which fraction is bigger.7 = 7, so 7/3 = 7/3
- Write the answer. =
Check. 2 1/3 = 7/3. ✓
Exercise 3C Practice: mixed numbers and improper fractions
Non-calculatorMethod. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 3 parts, so 1 wholes have 1 × 3 parts.1 × 3 = 3
- Add the top number. Add the 2 parts that are left over.3 + 2 = 5
- Keep the same bottom number. The size of each part does not change.5/3
- Write the answer. 5/3
Check. 5/3 = 1 2/3, because 1 × 3 + 2 = 5. ✓
Method. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 2 parts, so 3 wholes have 3 × 2 parts.3 × 2 = 6
- Add the top number. Add the 1 parts that are left over.6 + 1 = 7
- Keep the same bottom number. The size of each part does not change.7/2
- Write the answer. 7/2
Check. 7/2 = 3 1/2, because 3 × 2 + 1 = 7. ✓
Method. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 8 parts, so 2 wholes have 2 × 8 parts.2 × 8 = 16
- Add the top number. Add the 3 parts that are left over.16 + 3 = 19
- Keep the same bottom number. The size of each part does not change.19/8
- Write the answer. 19/8
Check. 19/8 = 2 3/8, because 2 × 8 + 3 = 19. ✓
Method. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 4 parts, so 5 wholes have 5 × 4 parts.5 × 4 = 20
- Add the top number. Add the 1 parts that are left over.20 + 1 = 21
- Keep the same bottom number. The size of each part does not change.21/4
- Write the answer. 21/4
Check. 21/4 = 5 1/4, because 5 × 4 + 1 = 21. ✓
Method. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 5 parts, so 4 wholes have 4 × 5 parts.4 × 5 = 20
- Add the top number. Add the 3 parts that are left over.20 + 3 = 23
- Keep the same bottom number. The size of each part does not change.23/5
- Write the answer. 23/5
Check. 23/5 = 4 3/5, because 4 × 5 + 3 = 23. ✓
Method. Multiply the whole number by the bottom, then add the top.
- Multiply the whole number by the bottom number. Each whole has 6 parts, so 2 wholes have 2 × 6 parts.2 × 6 = 12
- Add the top number. Add the 1 parts that are left over.12 + 1 = 13
- Keep the same bottom number. The size of each part does not change.13/6
- Write the answer. 13/6
Check. 13/6 = 2 1/6, because 2 × 6 + 1 = 13. ✓
Method. Divide the top by the bottom.
- Divide the top number by the bottom number. 11 ÷ 4 = 2 with 3 left over.11 ÷ 4 = 2 r 3
- Write the answer as a mixed number. The whole number is 2, and the 3 left over goes over 4.2 3/4
- Write the answer. 2 3/4
Check. 2 3/4, because the whole number times 4 plus the remainder is 11. ✓
Method. Divide the top by the bottom.
- Divide the top number by the bottom number. 17 ÷ 6 = 2 with 5 left over.17 ÷ 6 = 2 r 5
- Write the answer as a mixed number. The whole number is 2, and the 5 left over goes over 6.2 5/6
- Write the answer. 2 5/6
Check. 2 5/6, because the whole number times 6 plus the remainder is 17. ✓
Method. Divide the top by the bottom.
- Divide the top number by the bottom number. 23 ÷ 5 = 4 with 3 left over.23 ÷ 5 = 4 r 3
- Write the answer as a mixed number. The whole number is 4, and the 3 left over goes over 5.4 3/5
- Write the answer. 4 3/5
Check. 4 3/5, because the whole number times 5 plus the remainder is 23. ✓
Method. Divide the top by the bottom.
- Divide the top number by the bottom number. 14 ÷ 3 = 4 with 2 left over.14 ÷ 3 = 4 r 2
- Write the answer as a mixed number. The whole number is 4, and the 2 left over goes over 3.4 2/3
- Write the answer. 4 2/3
Check. 4 2/3, because the whole number times 3 plus the remainder is 14. ✓
Method. Divide the top by the bottom.
- Divide the top number by the bottom number. 19 ÷ 8 = 2 with 3 left over.19 ÷ 8 = 2 r 3
- Write the answer as a mixed number. The whole number is 2, and the 3 left over goes over 8.2 3/8
- Write the answer. 2 3/8
Check. 2 3/8, because the whole number times 8 plus the remainder is 19. ✓
Method. Change 4 3/8 to an improper fraction.
- Multiply the whole number by the bottom number. Each whole has 8 parts, so 4 wholes have 4 × 8 parts.4 × 8 = 32
- Add the top number. Add the 3 parts that are left over.32 + 3 = 35
- Keep the same bottom number. The size of each part does not change.35/8
- Write the answer. 35/8
Check. 35/8 = 4 3/8, and 35 ÷ 8 = 4 remainder 3. ✓
Method. Divide 50 by 7 and write the remainder over 7.
- Divide the top number by the bottom number. 50 ÷ 7 = 7 with 1 left over.50 ÷ 7 = 7 r 1
- Write the answer as a mixed number. The whole number is 7, and the 1 left over goes over 7.7 1/7
- Write the answer. 7 1/7
Check. 7 × 7 + 1 = 50, so 50/7 = 7 1/7. ✓
Method. Divide 9 by 4 and read the answer as wholes and parts.
- Divide. 9 ÷ 4 = 2 remainder 1.9 ÷ 4 = 2 r 1
- Read the answer. Two wholes and one quarter left over.2 1/4
- Write the answer. 9/4 means 9 quarters; 4 quarters make one whole, so 9 quarters is 2 wholes and 1 quarter.
Check. 2 × 4 + 1 = 9. ✓
Method. Divide 13 by 4.
- Divide the top number by the bottom number. 13 ÷ 4 = 3 with 1 left over.13 ÷ 4 = 3 r 1
- Write the answer as a mixed number. The whole number is 3, and the 1 left over goes over 4.3 1/4
- Write the answer. 3 1/4
Check. 3 × 4 + 1 = 13. ✓
Method. Multiply the whole number by 5, add 2, and keep the bottom.
- Multiply the whole number by the bottom number. Each whole has 5 parts, so 3 wholes have 3 × 5 parts.3 × 5 = 15
- Add the top number. Add the 2 parts that are left over.15 + 2 = 17
- Keep the same bottom number. The size of each part does not change.17/5
- Write the answer. 17/5
Check. 3 × 5 + 2 = 17. ✓