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 12 to make 20?
12 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 10 to make 100?
10 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 17 to make 100?
17 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 97 to make 100?
97 · 100 · 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 31 to make 50?
31 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
9. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 63 to make 100?
63 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 93 to make 100?
93 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104747 · 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 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.
2. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
3. How many more do you need to add to 10 to make 100?
90
Subtract 10 from 100: 100 − 10 = 90.
4. How many more do you need to add to 17 to make 100?
83
Subtract 17 from 100: 100 − 17 = 83.
5. How many more do you need to add to 97 to make 100?
3
Subtract 97 from 100: 100 − 97 = 3.
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 31 to make 50?
19
Subtract 31 from 50: 50 − 31 = 19.
8. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
9. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
10. How many more do you need to add to 63 to make 100?
37
Subtract 63 from 100: 100 − 63 = 37.
11. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
12. How many more do you need to add to 93 to make 100?
7
Subtract 93 from 100: 100 − 93 = 7.

12 questions · Seed 104747 · 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 12 to make 20?
12 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 10 to make 100?
10 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 17 to make 100?
17 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 97 to make 100?
97 · 100 · 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 31 to make 50?
31 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
9. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 63 to make 100?
63 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 93 to make 100?
93 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104747 · 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 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.
2. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
3. How many more do you need to add to 10 to make 100?
90
Subtract 10 from 100: 100 − 10 = 90.
4. How many more do you need to add to 17 to make 100?
83
Subtract 17 from 100: 100 − 17 = 83.
5. How many more do you need to add to 97 to make 100?
3
Subtract 97 from 100: 100 − 97 = 3.
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 31 to make 50?
19
Subtract 31 from 50: 50 − 31 = 19.
8. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
9. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
10. How many more do you need to add to 63 to make 100?
37
Subtract 63 from 100: 100 − 63 = 37.
11. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
12. How many more do you need to add to 93 to make 100?
7
Subtract 93 from 100: 100 − 93 = 7.

12 questions · Seed 104747 · Age guidance, not curriculum certification