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 18 to make 30?
18 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 50 to make 100?
50 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 10 to make 50?
10 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 20 to make 30?
20 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 37 to make 50?
37 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 22 to make 50?
22 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 47 to make 50?
47 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 11 to make 50?
11 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 11 to make 30?
11 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104779 · 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 18 to make 30?
12
Subtract 18 from 30: 30 − 18 = 12.
2. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
3. How many more do you need to add to 50 to make 100?
50
Subtract 50 from 100: 100 − 50 = 50.
4. How many more do you need to add to 10 to make 50?
40
Subtract 10 from 50: 50 − 10 = 40.
5. How many more do you need to add to 20 to make 30?
10
Subtract 20 from 30: 30 − 20 = 10.
6. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.
7. How many more do you need to add to 37 to make 50?
13
Subtract 37 from 50: 50 − 37 = 13.
8. How many more do you need to add to 22 to make 50?
28
Subtract 22 from 50: 50 − 22 = 28.
9. How many more do you need to add to 47 to make 50?
3
Subtract 47 from 50: 50 − 47 = 3.
10. How many more do you need to add to 11 to make 50?
39
Subtract 11 from 50: 50 − 11 = 39.
11. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
12. How many more do you need to add to 11 to make 30?
19
Subtract 11 from 30: 30 − 11 = 19.

12 questions · Seed 104779 · 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 18 to make 30?
18 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 50 to make 100?
50 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 10 to make 50?
10 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 20 to make 30?
20 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 37 to make 50?
37 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 22 to make 50?
22 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 47 to make 50?
47 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 11 to make 50?
11 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 11 to make 30?
11 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104779 · 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 18 to make 30?
12
Subtract 18 from 30: 30 − 18 = 12.
2. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
3. How many more do you need to add to 50 to make 100?
50
Subtract 50 from 100: 100 − 50 = 50.
4. How many more do you need to add to 10 to make 50?
40
Subtract 10 from 50: 50 − 10 = 40.
5. How many more do you need to add to 20 to make 30?
10
Subtract 20 from 30: 30 − 20 = 10.
6. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.
7. How many more do you need to add to 37 to make 50?
13
Subtract 37 from 50: 50 − 37 = 13.
8. How many more do you need to add to 22 to make 50?
28
Subtract 22 from 50: 50 − 22 = 28.
9. How many more do you need to add to 47 to make 50?
3
Subtract 47 from 50: 50 − 47 = 3.
10. How many more do you need to add to 11 to make 50?
39
Subtract 11 from 50: 50 − 11 = 39.
11. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
12. How many more do you need to add to 11 to make 30?
19
Subtract 11 from 30: 30 − 11 = 19.

12 questions · Seed 104779 · Age guidance, not curriculum certification