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 20 to make 30?
20 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 71 to make 100?
71 · 100 · Complements to 10, 20 & 100
3. How many more do you need to add to 5 to make 30?
5 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 24 to make 30?
24 · 30 · Complements to 10, 20 & 100
5. How many more do you need to add to 11 to make 100?
11 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
8. How many more do you need to add to 63 to make 100?
63 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 23 to make 100?
23 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 17 to make 30?
17 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 20?
2 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 10 to make 20?
10 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104785 · 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 20 to make 30?
10
Subtract 20 from 30: 30 − 20 = 10.
2. How many more do you need to add to 71 to make 100?
29
Subtract 71 from 100: 100 − 71 = 29.
3. How many more do you need to add to 5 to make 30?
25
Subtract 5 from 30: 30 − 5 = 25.
4. How many more do you need to add to 24 to make 30?
6
Subtract 24 from 30: 30 − 24 = 6.
5. How many more do you need to add to 11 to make 100?
89
Subtract 11 from 100: 100 − 11 = 89.
6. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
7. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
8. How many more do you need to add to 63 to make 100?
37
Subtract 63 from 100: 100 − 63 = 37.
9. How many more do you need to add to 23 to make 100?
77
Subtract 23 from 100: 100 − 23 = 77.
10. How many more do you need to add to 17 to make 30?
13
Subtract 17 from 30: 30 − 17 = 13.
11. How many more do you need to add to 2 to make 20?
18
Subtract 2 from 20: 20 − 2 = 18.
12. How many more do you need to add to 10 to make 20?
10
Subtract 10 from 20: 20 − 10 = 10.

12 questions · Seed 104785 · 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 20 to make 30?
20 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 71 to make 100?
71 · 100 · Complements to 10, 20 & 100
3. How many more do you need to add to 5 to make 30?
5 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 24 to make 30?
24 · 30 · Complements to 10, 20 & 100
5. How many more do you need to add to 11 to make 100?
11 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
8. How many more do you need to add to 63 to make 100?
63 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 23 to make 100?
23 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 17 to make 30?
17 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 20?
2 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 10 to make 20?
10 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104785 · 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 20 to make 30?
10
Subtract 20 from 30: 30 − 20 = 10.
2. How many more do you need to add to 71 to make 100?
29
Subtract 71 from 100: 100 − 71 = 29.
3. How many more do you need to add to 5 to make 30?
25
Subtract 5 from 30: 30 − 5 = 25.
4. How many more do you need to add to 24 to make 30?
6
Subtract 24 from 30: 30 − 24 = 6.
5. How many more do you need to add to 11 to make 100?
89
Subtract 11 from 100: 100 − 11 = 89.
6. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
7. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
8. How many more do you need to add to 63 to make 100?
37
Subtract 63 from 100: 100 − 63 = 37.
9. How many more do you need to add to 23 to make 100?
77
Subtract 23 from 100: 100 − 23 = 77.
10. How many more do you need to add to 17 to make 30?
13
Subtract 17 from 30: 30 − 17 = 13.
11. How many more do you need to add to 2 to make 20?
18
Subtract 2 from 20: 20 − 2 = 18.
12. How many more do you need to add to 10 to make 20?
10
Subtract 10 from 20: 20 − 10 = 10.

12 questions · Seed 104785 · Age guidance, not curriculum certification