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 27 to make 30?
27 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 76 to make 100?
76 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 78 to make 100?
78 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 28 to make 50?
28 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 42 to make 50?
42 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 14 to make 20?
14 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 89 to make 100?
89 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 16 to make 100?
16 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104786 · 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 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
2. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
3. How many more do you need to add to 76 to make 100?
24
Subtract 76 from 100: 100 − 76 = 24.
4. How many more do you need to add to 78 to make 100?
22
Subtract 78 from 100: 100 − 78 = 22.
5. How many more do you need to add to 28 to make 50?
22
Subtract 28 from 50: 50 − 28 = 22.
6. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
7. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.
8. How many more do you need to add to 42 to make 50?
8
Subtract 42 from 50: 50 − 42 = 8.
9. How many more do you need to add to 14 to make 20?
6
Subtract 14 from 20: 20 − 14 = 6.
10. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
11. How many more do you need to add to 89 to make 100?
11
Subtract 89 from 100: 100 − 89 = 11.
12. How many more do you need to add to 16 to make 100?
84
Subtract 16 from 100: 100 − 16 = 84.

12 questions · Seed 104786 · 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 27 to make 30?
27 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 76 to make 100?
76 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 78 to make 100?
78 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 28 to make 50?
28 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 42 to make 50?
42 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 14 to make 20?
14 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 89 to make 100?
89 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 16 to make 100?
16 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104786 · 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 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
2. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
3. How many more do you need to add to 76 to make 100?
24
Subtract 76 from 100: 100 − 76 = 24.
4. How many more do you need to add to 78 to make 100?
22
Subtract 78 from 100: 100 − 78 = 22.
5. How many more do you need to add to 28 to make 50?
22
Subtract 28 from 50: 50 − 28 = 22.
6. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
7. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.
8. How many more do you need to add to 42 to make 50?
8
Subtract 42 from 50: 50 − 42 = 8.
9. How many more do you need to add to 14 to make 20?
6
Subtract 14 from 20: 20 − 14 = 6.
10. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
11. How many more do you need to add to 89 to make 100?
11
Subtract 89 from 100: 100 − 89 = 11.
12. How many more do you need to add to 16 to make 100?
84
Subtract 16 from 100: 100 − 16 = 84.

12 questions · Seed 104786 · Age guidance, not curriculum certification