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 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 48 to make 100?
48 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 45 to make 50?
45 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 7 to make 100?
7 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 10 to make 30?
10 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 20 to make 50?
20 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
10. How many more do you need to add to 40 to make 50?
40 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 3 to make 20?
3 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 3 to make 50?
3 · 50 · Complements to 10, 20 & 100

12 questions · Seed 104777 · 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 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
3. How many more do you need to add to 48 to make 100?
52
Subtract 48 from 100: 100 − 48 = 52.
4. How many more do you need to add to 45 to make 50?
5
Subtract 45 from 50: 50 − 45 = 5.
5. How many more do you need to add to 7 to make 100?
93
Subtract 7 from 100: 100 − 7 = 93.
6. How many more do you need to add to 10 to make 30?
20
Subtract 10 from 30: 30 − 10 = 20.
7. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
8. How many more do you need to add to 20 to make 50?
30
Subtract 20 from 50: 50 − 20 = 30.
9. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
10. How many more do you need to add to 40 to make 50?
10
Subtract 40 from 50: 50 − 40 = 10.
11. How many more do you need to add to 3 to make 20?
17
Subtract 3 from 20: 20 − 3 = 17.
12. How many more do you need to add to 3 to make 50?
47
Subtract 3 from 50: 50 − 3 = 47.

12 questions · Seed 104777 · 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 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 48 to make 100?
48 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 45 to make 50?
45 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 7 to make 100?
7 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 10 to make 30?
10 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 20 to make 50?
20 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
10. How many more do you need to add to 40 to make 50?
40 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 3 to make 20?
3 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 3 to make 50?
3 · 50 · Complements to 10, 20 & 100

12 questions · Seed 104777 · 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 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
3. How many more do you need to add to 48 to make 100?
52
Subtract 48 from 100: 100 − 48 = 52.
4. How many more do you need to add to 45 to make 50?
5
Subtract 45 from 50: 50 − 45 = 5.
5. How many more do you need to add to 7 to make 100?
93
Subtract 7 from 100: 100 − 7 = 93.
6. How many more do you need to add to 10 to make 30?
20
Subtract 10 from 30: 30 − 10 = 20.
7. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
8. How many more do you need to add to 20 to make 50?
30
Subtract 20 from 50: 50 − 20 = 30.
9. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
10. How many more do you need to add to 40 to make 50?
10
Subtract 40 from 50: 50 − 40 = 10.
11. How many more do you need to add to 3 to make 20?
17
Subtract 3 from 20: 20 − 3 = 17.
12. How many more do you need to add to 3 to make 50?
47
Subtract 3 from 50: 50 − 3 = 47.

12 questions · Seed 104777 · Age guidance, not curriculum certification