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.

Choose “Save as PDF” to keep a copy. Use your browser’s paper setting for A4 or Letter.

Worksheet StudioPractice pack · Ages 7-9

Take your time. Show your thinking.

1. How many more do you need to add to 19 to make 100?
19 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 7 to make 20?
7 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 43 to make 100?
43 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 53 to make 100?
53 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 2 to make 30?
2 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 22 to make 50?
22 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 7 to make 100?
7 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 48 to make 50?
48 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 47 to make 100?
47 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 23 to make 30?
23 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104738 · 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 19 to make 100?
81
Subtract 19 from 100: 100 − 19 = 81.
2. How many more do you need to add to 7 to make 20?
13
Subtract 7 from 20: 20 − 7 = 13.
3. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
4. How many more do you need to add to 43 to make 100?
57
Subtract 43 from 100: 100 − 43 = 57.
5. How many more do you need to add to 53 to make 100?
47
Subtract 53 from 100: 100 − 53 = 47.
6. How many more do you need to add to 2 to make 30?
28
Subtract 2 from 30: 30 − 2 = 28.
7. How many more do you need to add to 22 to make 50?
28
Subtract 22 from 50: 50 − 22 = 28.
8. How many more do you need to add to 7 to make 100?
93
Subtract 7 from 100: 100 − 7 = 93.
9. How many more do you need to add to 48 to make 50?
2
Subtract 48 from 50: 50 − 48 = 2.
10. How many more do you need to add to 47 to make 100?
53
Subtract 47 from 100: 100 − 47 = 53.
11. How many more do you need to add to 23 to make 30?
7
Subtract 23 from 30: 30 − 23 = 7.
12. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.

12 questions · Seed 104738 · 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 19 to make 100?
19 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 7 to make 20?
7 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 43 to make 100?
43 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 53 to make 100?
53 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 2 to make 30?
2 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 22 to make 50?
22 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 7 to make 100?
7 · 100 · Complements to 10, 20 & 100
9. How many more do you need to add to 48 to make 50?
48 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 47 to make 100?
47 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 23 to make 30?
23 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 12 to make 100?
12 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104738 · 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 19 to make 100?
81
Subtract 19 from 100: 100 − 19 = 81.
2. How many more do you need to add to 7 to make 20?
13
Subtract 7 from 20: 20 − 7 = 13.
3. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
4. How many more do you need to add to 43 to make 100?
57
Subtract 43 from 100: 100 − 43 = 57.
5. How many more do you need to add to 53 to make 100?
47
Subtract 53 from 100: 100 − 53 = 47.
6. How many more do you need to add to 2 to make 30?
28
Subtract 2 from 30: 30 − 2 = 28.
7. How many more do you need to add to 22 to make 50?
28
Subtract 22 from 50: 50 − 22 = 28.
8. How many more do you need to add to 7 to make 100?
93
Subtract 7 from 100: 100 − 7 = 93.
9. How many more do you need to add to 48 to make 50?
2
Subtract 48 from 50: 50 − 48 = 2.
10. How many more do you need to add to 47 to make 100?
53
Subtract 47 from 100: 100 − 47 = 53.
11. How many more do you need to add to 23 to make 30?
7
Subtract 23 from 30: 30 − 23 = 7.
12. How many more do you need to add to 12 to make 100?
88
Subtract 12 from 100: 100 − 12 = 88.

12 questions · Seed 104738 · Age guidance, not curriculum certification