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 15 to make 50?
15 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 11 to make 30?
11 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 14 to make 50?
14 · 50 · Complements to 10, 20 & 100
7. How many more do you need to add to 3 to make 50?
3 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 17 to make 50?
17 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 42 to make 100?
42 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 90 to make 100?
90 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 4 to make 50?
4 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104750 · 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 15 to make 50?
35
Subtract 15 from 50: 50 − 15 = 35.
2. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
3. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
4. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
5. How many more do you need to add to 11 to make 30?
19
Subtract 11 from 30: 30 − 11 = 19.
6. How many more do you need to add to 14 to make 50?
36
Subtract 14 from 50: 50 − 14 = 36.
7. How many more do you need to add to 3 to make 50?
47
Subtract 3 from 50: 50 − 3 = 47.
8. How many more do you need to add to 17 to make 50?
33
Subtract 17 from 50: 50 − 17 = 33.
9. How many more do you need to add to 42 to make 100?
58
Subtract 42 from 100: 100 − 42 = 58.
10. How many more do you need to add to 90 to make 100?
10
Subtract 90 from 100: 100 − 90 = 10.
11. How many more do you need to add to 4 to make 50?
46
Subtract 4 from 50: 50 − 4 = 46.
12. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.

12 questions · Seed 104750 · 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 15 to make 50?
15 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 11 to make 30?
11 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 14 to make 50?
14 · 50 · Complements to 10, 20 & 100
7. How many more do you need to add to 3 to make 50?
3 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 17 to make 50?
17 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 42 to make 100?
42 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 90 to make 100?
90 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 4 to make 50?
4 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104750 · 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 15 to make 50?
35
Subtract 15 from 50: 50 − 15 = 35.
2. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
3. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
4. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
5. How many more do you need to add to 11 to make 30?
19
Subtract 11 from 30: 30 − 11 = 19.
6. How many more do you need to add to 14 to make 50?
36
Subtract 14 from 50: 50 − 14 = 36.
7. How many more do you need to add to 3 to make 50?
47
Subtract 3 from 50: 50 − 3 = 47.
8. How many more do you need to add to 17 to make 50?
33
Subtract 17 from 50: 50 − 17 = 33.
9. How many more do you need to add to 42 to make 100?
58
Subtract 42 from 100: 100 − 42 = 58.
10. How many more do you need to add to 90 to make 100?
10
Subtract 90 from 100: 100 − 90 = 10.
11. How many more do you need to add to 4 to make 50?
46
Subtract 4 from 50: 50 − 4 = 46.
12. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.

12 questions · Seed 104750 · Age guidance, not curriculum certification