Step-by-step Maths Level 5: Subtracting fractions with the same denominator
Part of the Step-by-step Maths Level 5 adding and subtracting fractions with the same denominator chapter. Chapter overview · whole chapter on one page
Subtracting fractions with the same denominator
Subtract the top numbers and keep the bottom number: 7/8 - 2/8 = 5/8.
Simplify the answer if you can: 6/8 - 2/8 = 4/8 = 1/2.
Key ideas
- Subtract the top numbers; keep the bottom number.
- Simplify the answer if you can.
- Check by adding back.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.7 - 2 = 5
- Keep the bottom number 8. The parts are the same size, so the bottom number does not change.5/8
- Write the answer. This is the simplest form.5/8
Check. Check: 5/8 + 2/8 gives 7/8.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.6 - 2 = 4
- Keep the bottom number 8. The parts are the same size, so the bottom number does not change.4/8
- Simplify. Divide the top and bottom by 4.4/8 = 1/2
- Write the answer. This is the simplest form.1/2
Check. Check: 1/2 + 2/8 gives 6/8.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.9 - 4 = 5
- Keep the bottom number 10. The parts are the same size, so the bottom number does not change.5/10
- Simplify. Divide the top and bottom by 5.5/10 = 1/2
- Write the answer. This is the simplest form.1/2
Check. Check: 1/2 + 4/10 gives 9/10.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Watch out
Watch out. 7/8 - 2/8 is 5/8. Do not write 5/6, and do not subtract the bottom numbers.
Exam tip
Grown-up tip. Use a bar cut into 8 parts. Take away 2 parts and count what is left.
Exercise 6C Practice: subtracting fractions
Non-calculatorMethod. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.2 - 1 = 1
- Keep the bottom number 5. The parts are the same size, so the bottom number does not change.1/5
- Write the answer. This is the simplest form.1/5
Check. Check: 1/5 + 1/5 gives 2/5.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.2 - 1 = 1
- Keep the bottom number 6. The parts are the same size, so the bottom number does not change.1/6
- Write the answer. This is the simplest form.1/6
Check. Check: 1/6 + 1/6 gives 2/6.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.4 - 2 = 2
- Keep the bottom number 5. The parts are the same size, so the bottom number does not change.2/5
- Write the answer. This is the simplest form.2/5
Check. Check: 2/5 + 2/5 gives 4/5.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.3 - 1 = 2
- Keep the bottom number 4. The parts are the same size, so the bottom number does not change.2/4
- Simplify. Divide the top and bottom by 2.2/4 = 1/2
- Write the answer. This is the simplest form.1/2
Check. Check: 1/2 + 1/4 gives 3/4.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.8 - 4 = 4
- Keep the bottom number 10. The parts are the same size, so the bottom number does not change.4/10
- Simplify. Divide the top and bottom by 2.4/10 = 2/5
- Write the answer. This is the simplest form.2/5
Check. Check: 2/5 + 4/10 gives 8/10.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.6 - 2 = 4
- Keep the bottom number 8. The parts are the same size, so the bottom number does not change.4/8
- Simplify. Divide the top and bottom by 4.4/8 = 1/2
- Write the answer. This is the simplest form.1/2
Check. Check: 1/2 + 2/8 gives 6/8.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.9 - 7 = 2
- Keep the bottom number 10. The parts are the same size, so the bottom number does not change.2/10
- Simplify. Divide the top and bottom by 2.2/10 = 1/5
- Write the answer. This is the simplest form.1/5
Check. Check: 1/5 + 7/10 gives 9/10.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.2 - 1 = 1
- Keep the bottom number 4. The parts are the same size, so the bottom number does not change.1/4
- Write the answer. This is the simplest form.1/4
Check. Check: 1/4 + 1/4 gives 2/4.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.5 - 2 = 3
- Keep the bottom number 6. The parts are the same size, so the bottom number does not change.3/6
- Simplify. Divide the top and bottom by 3.3/6 = 1/2
- Write the answer. This is the simplest form.1/2
Check. Check: 1/2 + 2/6 gives 5/6.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.3 - 2 = 1
- Keep the bottom number 4. The parts are the same size, so the bottom number does not change.1/4
- Write the answer. This is the simplest form.1/4
Check. Check: 1/4 + 2/4 gives 3/4.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.9 - 4 = 5
- Keep the bottom number 10. The parts are the same size, so the bottom number does not change.5/10
- Simplify. Divide the top and bottom by 5.5/10 = 1/2
- Write the answer. This is the simplest form.1/2
Check. Check: 1/2 + 4/10 gives 9/10.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.3 - 1 = 2
- Keep the bottom number 6. The parts are the same size, so the bottom number does not change.2/6
- Simplify. Divide the top and bottom by 2.2/6 = 1/3
- Write the answer. This is the simplest form.1/3
Check. Check: 1/3 + 1/6 gives 3/6.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.6 - 3 = 3
- Keep the bottom number 8. The parts are the same size, so the bottom number does not change.3/8
- Write the answer. This is the simplest form.3/8
Check. Check: 3/8 + 3/8 gives 6/8.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.4 - 1 = 3
- Keep the bottom number 5. The parts are the same size, so the bottom number does not change.3/5
- Write the answer. This is the simplest form.3/5
Check. Check: 3/5 + 1/5 gives 4/5.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.5 - 4 = 1
- Keep the bottom number 6. The parts are the same size, so the bottom number does not change.1/6
- Write the answer. This is the simplest form.1/6
Check. Check: 1/6 + 4/6 gives 5/6.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.
Method. Subtract the top numbers and keep the bottom number. Simplify if you can.
- Subtract the top numbers. The bottom number stays the same.4 - 3 = 1
- Keep the bottom number 6. The parts are the same size, so the bottom number does not change.1/6
- Write the answer. This is the simplest form.1/6
Check. Check: 1/6 + 3/6 gives 4/6.
Watch out. Do not subtract the bottom numbers. 7/8 - 3/8 is 4/8, which is 1/2.