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 25 to make 100?
25 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 35 to make 50?
35 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 19 to make 30?
19 · 30 · Complements to 10, 20 & 100
5. How many more do you need to add to 45 to make 50?
45 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 5 to make 50?
5 · 50 · Complements to 10, 20 & 100
7. How many more do you need to add to 22 to make 100?
22 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 26 to make 50?
26 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 14 to make 30?
14 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 13 to make 30?
13 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104782 · 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 25 to make 100?
75
Subtract 25 from 100: 100 − 25 = 75.
2. How many more do you need to add to 35 to make 50?
15
Subtract 35 from 50: 50 − 35 = 15.
3. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
4. How many more do you need to add to 19 to make 30?
11
Subtract 19 from 30: 30 − 19 = 11.
5. How many more do you need to add to 45 to make 50?
5
Subtract 45 from 50: 50 − 45 = 5.
6. How many more do you need to add to 5 to make 50?
45
Subtract 5 from 50: 50 − 5 = 45.
7. How many more do you need to add to 22 to make 100?
78
Subtract 22 from 100: 100 − 22 = 78.
8. How many more do you need to add to 26 to make 50?
24
Subtract 26 from 50: 50 − 26 = 24.
9. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
10. How many more do you need to add to 14 to make 30?
16
Subtract 14 from 30: 30 − 14 = 16.
11. How many more do you need to add to 13 to make 30?
17
Subtract 13 from 30: 30 − 13 = 17.
12. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.

12 questions · Seed 104782 · 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 25 to make 100?
25 · 100 · Complements to 10, 20 & 100
2. How many more do you need to add to 35 to make 50?
35 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 19 to make 30?
19 · 30 · Complements to 10, 20 & 100
5. How many more do you need to add to 45 to make 50?
45 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 5 to make 50?
5 · 50 · Complements to 10, 20 & 100
7. How many more do you need to add to 22 to make 100?
22 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 26 to make 50?
26 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 14 to make 30?
14 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 13 to make 30?
13 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104782 · 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 25 to make 100?
75
Subtract 25 from 100: 100 − 25 = 75.
2. How many more do you need to add to 35 to make 50?
15
Subtract 35 from 50: 50 − 35 = 15.
3. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
4. How many more do you need to add to 19 to make 30?
11
Subtract 19 from 30: 30 − 19 = 11.
5. How many more do you need to add to 45 to make 50?
5
Subtract 45 from 50: 50 − 45 = 5.
6. How many more do you need to add to 5 to make 50?
45
Subtract 5 from 50: 50 − 5 = 45.
7. How many more do you need to add to 22 to make 100?
78
Subtract 22 from 100: 100 − 22 = 78.
8. How many more do you need to add to 26 to make 50?
24
Subtract 26 from 50: 50 − 26 = 24.
9. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
10. How many more do you need to add to 14 to make 30?
16
Subtract 14 from 30: 30 − 14 = 16.
11. How many more do you need to add to 13 to make 30?
17
Subtract 13 from 30: 30 − 13 = 17.
12. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.

12 questions · Seed 104782 · Age guidance, not curriculum certification