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 12 to make 20?
12 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 73 to make 100?
73 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 11 to make 30?
11 · 30 · Complements to 10, 20 & 100
5. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 45 to make 100?
45 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 21 to make 50?
21 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 97 to make 100?
97 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 12 to make 30?
12 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 98 to make 100?
98 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 3 to make 30?
3 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104765 · 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 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.
2. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
3. How many more do you need to add to 73 to make 100?
27
Subtract 73 from 100: 100 − 73 = 27.
4. How many more do you need to add to 11 to make 30?
19
Subtract 11 from 30: 30 − 11 = 19.
5. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
6. How many more do you need to add to 45 to make 100?
55
Subtract 45 from 100: 100 − 45 = 55.
7. How many more do you need to add to 21 to make 50?
29
Subtract 21 from 50: 50 − 21 = 29.
8. How many more do you need to add to 97 to make 100?
3
Subtract 97 from 100: 100 − 97 = 3.
9. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
10. How many more do you need to add to 12 to make 30?
18
Subtract 12 from 30: 30 − 12 = 18.
11. How many more do you need to add to 98 to make 100?
2
Subtract 98 from 100: 100 − 98 = 2.
12. How many more do you need to add to 3 to make 30?
27
Subtract 3 from 30: 30 − 3 = 27.

12 questions · Seed 104765 · 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 12 to make 20?
12 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 73 to make 100?
73 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 11 to make 30?
11 · 30 · Complements to 10, 20 & 100
5. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 45 to make 100?
45 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 21 to make 50?
21 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 97 to make 100?
97 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 12 to make 30?
12 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 98 to make 100?
98 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 3 to make 30?
3 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104765 · 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 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.
2. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
3. How many more do you need to add to 73 to make 100?
27
Subtract 73 from 100: 100 − 73 = 27.
4. How many more do you need to add to 11 to make 30?
19
Subtract 11 from 30: 30 − 11 = 19.
5. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
6. How many more do you need to add to 45 to make 100?
55
Subtract 45 from 100: 100 − 45 = 55.
7. How many more do you need to add to 21 to make 50?
29
Subtract 21 from 50: 50 − 21 = 29.
8. How many more do you need to add to 97 to make 100?
3
Subtract 97 from 100: 100 − 97 = 3.
9. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
10. How many more do you need to add to 12 to make 30?
18
Subtract 12 from 30: 30 − 12 = 18.
11. How many more do you need to add to 98 to make 100?
2
Subtract 98 from 100: 100 − 98 = 2.
12. How many more do you need to add to 3 to make 30?
27
Subtract 3 from 30: 30 − 3 = 27.

12 questions · Seed 104765 · Age guidance, not curriculum certification