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 21 to make 50?
21 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 3 to make 30?
3 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 14 to make 30?
14 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 91 to make 100?
91 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 29 to make 30?
29 · 30 · Complements to 10, 20 & 100
8. How many more do you need to add to 9 to make 20?
9 · 20 · 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 5 to make 20?
5 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 30?
2 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 25 to make 30?
25 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104755 · 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 21 to make 50?
29
Subtract 21 from 50: 50 − 21 = 29.
2. How many more do you need to add to 3 to make 30?
27
Subtract 3 from 30: 30 − 3 = 27.
3. How many more do you need to add to 14 to make 30?
16
Subtract 14 from 30: 30 − 14 = 16.
4. How many more do you need to add to 91 to make 100?
9
Subtract 91 from 100: 100 − 91 = 9.
5. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
6. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
7. How many more do you need to add to 29 to make 30?
1
Subtract 29 from 30: 30 − 29 = 1.
8. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
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 5 to make 20?
15
Subtract 5 from 20: 20 − 5 = 15.
11. How many more do you need to add to 2 to make 30?
28
Subtract 2 from 30: 30 − 2 = 28.
12. How many more do you need to add to 25 to make 30?
5
Subtract 25 from 30: 30 − 25 = 5.

12 questions · Seed 104755 · 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 21 to make 50?
21 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 3 to make 30?
3 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 14 to make 30?
14 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 91 to make 100?
91 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 29 to make 30?
29 · 30 · Complements to 10, 20 & 100
8. How many more do you need to add to 9 to make 20?
9 · 20 · 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 5 to make 20?
5 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 30?
2 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 25 to make 30?
25 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104755 · 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 21 to make 50?
29
Subtract 21 from 50: 50 − 21 = 29.
2. How many more do you need to add to 3 to make 30?
27
Subtract 3 from 30: 30 − 3 = 27.
3. How many more do you need to add to 14 to make 30?
16
Subtract 14 from 30: 30 − 14 = 16.
4. How many more do you need to add to 91 to make 100?
9
Subtract 91 from 100: 100 − 91 = 9.
5. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
6. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
7. How many more do you need to add to 29 to make 30?
1
Subtract 29 from 30: 30 − 29 = 1.
8. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
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 5 to make 20?
15
Subtract 5 from 20: 20 − 5 = 15.
11. How many more do you need to add to 2 to make 30?
28
Subtract 2 from 30: 30 − 2 = 28.
12. How many more do you need to add to 25 to make 30?
5
Subtract 25 from 30: 30 − 25 = 5.

12 questions · Seed 104755 · Age guidance, not curriculum certification