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 20?
15 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 27 to make 30?
27 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 31 to make 50?
31 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 16 to make 30?
16 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 37 to make 100?
37 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 13 to make 30?
13 · 30 · Complements to 10, 20 & 100
9. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 47 to make 50?
47 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104729 · 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 20?
5
Subtract 15 from 20: 20 − 15 = 5.
2. How many more do you need to add to 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
3. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
4. How many more do you need to add to 31 to make 50?
19
Subtract 31 from 50: 50 − 31 = 19.
5. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
6. How many more do you need to add to 16 to make 30?
14
Subtract 16 from 30: 30 − 16 = 14.
7. How many more do you need to add to 37 to make 100?
63
Subtract 37 from 100: 100 − 37 = 63.
8. How many more do you need to add to 13 to make 30?
17
Subtract 13 from 30: 30 − 13 = 17.
9. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
10. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
11. How many more do you need to add to 47 to make 50?
3
Subtract 47 from 50: 50 − 47 = 3.
12. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.

12 questions · Seed 104729 · 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 20?
15 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 27 to make 30?
27 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 31 to make 50?
31 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 16 to make 30?
16 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 37 to make 100?
37 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 13 to make 30?
13 · 30 · Complements to 10, 20 & 100
9. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 47 to make 50?
47 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104729 · 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 20?
5
Subtract 15 from 20: 20 − 15 = 5.
2. How many more do you need to add to 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
3. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
4. How many more do you need to add to 31 to make 50?
19
Subtract 31 from 50: 50 − 31 = 19.
5. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
6. How many more do you need to add to 16 to make 30?
14
Subtract 16 from 30: 30 − 16 = 14.
7. How many more do you need to add to 37 to make 100?
63
Subtract 37 from 100: 100 − 37 = 63.
8. How many more do you need to add to 13 to make 30?
17
Subtract 13 from 30: 30 − 13 = 17.
9. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
10. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
11. How many more do you need to add to 47 to make 50?
3
Subtract 47 from 50: 50 − 47 = 3.
12. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.

12 questions · Seed 104729 · Age guidance, not curriculum certification