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 73 to make 100?
73 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 5 to make 50?
5 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 21 to make 30?
21 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 7 to make 30?
7 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 27 to make 30?
27 · 30 · 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 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
9. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 44 to make 50?
44 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 34 to make 50?
34 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 34 to make 100?
34 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104740 · 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 73 to make 100?
27
Subtract 73 from 100: 100 − 73 = 27.
2. How many more do you need to add to 5 to make 50?
45
Subtract 5 from 50: 50 − 5 = 45.
3. How many more do you need to add to 21 to make 30?
9
Subtract 21 from 30: 30 − 21 = 9.
4. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
5. How many more do you need to add to 7 to make 30?
23
Subtract 7 from 30: 30 − 7 = 23.
6. How many more do you need to add to 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
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 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
9. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
10. How many more do you need to add to 44 to make 50?
6
Subtract 44 from 50: 50 − 44 = 6.
11. How many more do you need to add to 34 to make 50?
16
Subtract 34 from 50: 50 − 34 = 16.
12. How many more do you need to add to 34 to make 100?
66
Subtract 34 from 100: 100 − 34 = 66.

12 questions · Seed 104740 · 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 73 to make 100?
73 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 5 to make 50?
5 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 21 to make 30?
21 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 7 to make 30?
7 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 27 to make 30?
27 · 30 · 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 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
9. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 44 to make 50?
44 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 34 to make 50?
34 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 34 to make 100?
34 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104740 · 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 73 to make 100?
27
Subtract 73 from 100: 100 − 73 = 27.
2. How many more do you need to add to 5 to make 50?
45
Subtract 5 from 50: 50 − 5 = 45.
3. How many more do you need to add to 21 to make 30?
9
Subtract 21 from 30: 30 − 21 = 9.
4. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
5. How many more do you need to add to 7 to make 30?
23
Subtract 7 from 30: 30 − 7 = 23.
6. How many more do you need to add to 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
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 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
9. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
10. How many more do you need to add to 44 to make 50?
6
Subtract 44 from 50: 50 − 44 = 6.
11. How many more do you need to add to 34 to make 50?
16
Subtract 34 from 50: 50 − 34 = 16.
12. How many more do you need to add to 34 to make 100?
66
Subtract 34 from 100: 100 − 34 = 66.

12 questions · Seed 104740 · Age guidance, not curriculum certification