MathsAges 7-9

Complements to 10, 20 & 100

Find how many more are needed to complete a benchmark number such as 10, 20, 50 or 100. Review suitability for your learners before teaching.

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Worksheet StudioPractice pack · Ages 7-9

Take your time. Show your thinking.

1. How many more do you need to add to 40 to make 100?
40 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 40 to make 50?
40 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 34 to make 50?
34 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 29 to make 30?
29 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 10 to make 20?
10 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 19 to make 100?
19 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 44 to make 50?
44 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 12 to make 20?
12 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104768 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 7-9

Answers and reasoning. Review before teaching.

1. How many more do you need to add to 40 to make 100?
60
Subtract 40 from 100: 100 − 40 = 60.
2. How many more do you need to add to 40 to make 50?
10
Subtract 40 from 50: 50 − 40 = 10.
3. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
4. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
5. How many more do you need to add to 34 to make 50?
16
Subtract 34 from 50: 50 − 34 = 16.
6. How many more do you need to add to 29 to make 30?
1
Subtract 29 from 30: 30 − 29 = 1.
7. How many more do you need to add to 10 to make 20?
10
Subtract 10 from 20: 20 − 10 = 10.
8. How many more do you need to add to 19 to make 100?
81
Subtract 19 from 100: 100 − 19 = 81.
9. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
10. How many more do you need to add to 44 to make 50?
6
Subtract 44 from 50: 50 − 44 = 6.
11. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
12. How many more do you need to add to 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.

12 questions · Seed 104768 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 7-9

Take your time. Show your thinking.

1. How many more do you need to add to 40 to make 100?
40 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 40 to make 50?
40 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 34 to make 50?
34 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 29 to make 30?
29 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 10 to make 20?
10 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 19 to make 100?
19 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 44 to make 50?
44 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 12 to make 20?
12 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104768 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 7-9

Answers and reasoning. Review before teaching.

1. How many more do you need to add to 40 to make 100?
60
Subtract 40 from 100: 100 − 40 = 60.
2. How many more do you need to add to 40 to make 50?
10
Subtract 40 from 50: 50 − 40 = 10.
3. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
4. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
5. How many more do you need to add to 34 to make 50?
16
Subtract 34 from 50: 50 − 34 = 16.
6. How many more do you need to add to 29 to make 30?
1
Subtract 29 from 30: 30 − 29 = 1.
7. How many more do you need to add to 10 to make 20?
10
Subtract 10 from 20: 20 − 10 = 10.
8. How many more do you need to add to 19 to make 100?
81
Subtract 19 from 100: 100 − 19 = 81.
9. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
10. How many more do you need to add to 44 to make 50?
6
Subtract 44 from 50: 50 − 44 = 6.
11. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
12. How many more do you need to add to 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.

12 questions · Seed 104768 · Age guidance, not curriculum certification