Step-by-step Maths Level 1: Taking away within 20
Part of the Step-by-step Maths Level 1 number stories within 20 chapter. Chapter overview · whole chapter on one page
Taking away within 20
To take away from a number up to 20, start at the bigger number. Count back, one at a time.
You can count back the first part to ten, then count back the rest.
Key ideas
- Start at the number you take from.
- Count back the number taken away.
- The answer is what is left.
Method. Start at 15 and count back 3.
- Start at 15. This is the number we take from.15
- Count back 3. Fourteen, thirteen, twelve.14, 13, 12
- Write the answer. 12
Check. 12 + 3 = 15. It works.
Watch out. Count back, to the left.
Method. Count back 5 from 18, one step at a time.
- Start at 18. This is the number we take from.18
- Count back 5. Seventeen, sixteen, fifteen, fourteen, thirteen.17, 16, 15, 14, 13
- Write the answer. 13
Check. 13 + 5 = 18. It works.
Watch out. Count the jumps, not the numbers you say.
Method. Take away the 6 that break.
- Start with 14. Mei has fourteen pencils.14
- Take away 6. Six break, so take them away.14 - 6 = 8
- Write the answer. 8
Check. 8 + 6 = 14. It works.
Watch out. Take away the ones that break.
Watch out
Watch out. Count back, not on. 15 − 3 is 12, not 18.
Exam tip
Grown-up tip. Use a number line from 0 to 20. Start at the number and move left, one step at a time.
Exercise 9C Taking away within 20
Non-calculatorMethod. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.16
- Take away 7. Cross out or count back this many.16 - 7
- Write the answer. This is how many are left.9
Check. Add back: 9 + 7 = 16. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.17
- Take away 4. Cross out or count back this many.17 - 4
- Write the answer. This is how many are left.13
Check. Add back: 13 + 4 = 17. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.18
- Take away 3. Cross out or count back this many.18 - 3
- Write the answer. This is how many are left.15
Check. Add back: 15 + 3 = 18. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.15
- Take away 2. Cross out or count back this many.15 - 2
- Write the answer. This is how many are left.13
Check. Add back: 13 + 2 = 15. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.15
- Take away 9. Cross out or count back this many.15 - 9
- Write the answer. This is how many are left.6
Check. Add back: 6 + 9 = 15. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.11
- Take away 4. Cross out or count back this many.11 - 4
- Write the answer. This is how many are left.7
Check. Add back: 7 + 4 = 11. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.17
- Take away 9. Cross out or count back this many.17 - 9
- Write the answer. This is how many are left.8
Check. Add back: 8 + 9 = 17. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.16
- Take away 8. Cross out or count back this many.16 - 8
- Write the answer. This is how many are left.8
Check. Add back: 8 + 8 = 16. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.20
- Take away 2. Cross out or count back this many.20 - 2
- Write the answer. This is how many are left.18
Check. Add back: 18 + 2 = 20. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.11
- Take away 8. Cross out or count back this many.11 - 8
- Write the answer. This is how many are left.3
Check. Add back: 3 + 8 = 11. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.18
- Take away 4. Cross out or count back this many.18 - 4
- Write the answer. This is how many are left.14
Check. Add back: 14 + 4 = 18. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.20
- Take away 4. Cross out or count back this many.20 - 4
- Write the answer. This is how many are left.16
Check. Add back: 16 + 4 = 20. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.15
- Take away 4. Cross out or count back this many.15 - 4
- Write the answer. This is how many are left.11
Check. Add back: 11 + 4 = 15. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.12
- Take away 7. Cross out or count back this many.12 - 7
- Write the answer. This is how many are left.5
Check. Add back: 5 + 7 = 12. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.14
- Take away 5. Cross out or count back this many.14 - 5
- Write the answer. This is how many are left.9
Check. Add back: 9 + 5 = 14. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.20
- Take away 5. Cross out or count back this many.20 - 5
- Write the answer. This is how many are left.15
Check. Add back: 15 + 5 = 20. The answer is right.
Watch out. Count back from the first number, not up from the second.