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 91 to make 100?
91 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 7 to make 30?
7 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 83 to make 100?
83 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 61 to make 100?
61 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 44 to make 100?
44 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 82 to make 100?
82 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
9. How many more do you need to add to 43 to make 100?
43 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 14 to make 50?
14 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 23 to make 50?
23 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 13 to make 30?
13 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104731 · 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 91 to make 100?
9
Subtract 91 from 100: 100 − 91 = 9.
2. How many more do you need to add to 7 to make 30?
23
Subtract 7 from 30: 30 − 7 = 23.
3. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.
4. How many more do you need to add to 83 to make 100?
17
Subtract 83 from 100: 100 − 83 = 17.
5. How many more do you need to add to 61 to make 100?
39
Subtract 61 from 100: 100 − 61 = 39.
6. How many more do you need to add to 44 to make 100?
56
Subtract 44 from 100: 100 − 44 = 56.
7. How many more do you need to add to 82 to make 100?
18
Subtract 82 from 100: 100 − 82 = 18.
8. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
9. How many more do you need to add to 43 to make 100?
57
Subtract 43 from 100: 100 − 43 = 57.
10. How many more do you need to add to 14 to make 50?
36
Subtract 14 from 50: 50 − 14 = 36.
11. How many more do you need to add to 23 to make 50?
27
Subtract 23 from 50: 50 − 23 = 27.
12. How many more do you need to add to 13 to make 30?
17
Subtract 13 from 30: 30 − 13 = 17.

12 questions · Seed 104731 · 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 91 to make 100?
91 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 7 to make 30?
7 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 83 to make 100?
83 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 61 to make 100?
61 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 44 to make 100?
44 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 82 to make 100?
82 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
9. How many more do you need to add to 43 to make 100?
43 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 14 to make 50?
14 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 23 to make 50?
23 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 13 to make 30?
13 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104731 · 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 91 to make 100?
9
Subtract 91 from 100: 100 − 91 = 9.
2. How many more do you need to add to 7 to make 30?
23
Subtract 7 from 30: 30 − 7 = 23.
3. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.
4. How many more do you need to add to 83 to make 100?
17
Subtract 83 from 100: 100 − 83 = 17.
5. How many more do you need to add to 61 to make 100?
39
Subtract 61 from 100: 100 − 61 = 39.
6. How many more do you need to add to 44 to make 100?
56
Subtract 44 from 100: 100 − 44 = 56.
7. How many more do you need to add to 82 to make 100?
18
Subtract 82 from 100: 100 − 82 = 18.
8. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
9. How many more do you need to add to 43 to make 100?
57
Subtract 43 from 100: 100 − 43 = 57.
10. How many more do you need to add to 14 to make 50?
36
Subtract 14 from 50: 50 − 14 = 36.
11. How many more do you need to add to 23 to make 50?
27
Subtract 23 from 50: 50 − 23 = 27.
12. How many more do you need to add to 13 to make 30?
17
Subtract 13 from 30: 30 − 13 = 17.

12 questions · Seed 104731 · Age guidance, not curriculum certification