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 4 to make 50?
4 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 28 to make 100?
28 · 100 · Complements to 10, 20 & 100
3. How many more do you need to add to 13 to make 50?
13 · 50 · Complements to 10, 20 & 100
4. How many more do you need to add to 34 to make 50?
34 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 5 to make 100?
5 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
9. How many more do you need to add to 39 to make 50?
39 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 28 to make 30?
28 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 15 to make 100?
15 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104783 · 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 4 to make 50?
46
Subtract 4 from 50: 50 − 4 = 46.
2. How many more do you need to add to 28 to make 100?
72
Subtract 28 from 100: 100 − 28 = 72.
3. How many more do you need to add to 13 to make 50?
37
Subtract 13 from 50: 50 − 13 = 37.
4. How many more do you need to add to 34 to make 50?
16
Subtract 34 from 50: 50 − 34 = 16.
5. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
6. How many more do you need to add to 5 to make 100?
95
Subtract 5 from 100: 100 − 5 = 95.
7. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
8. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
9. How many more do you need to add to 39 to make 50?
11
Subtract 39 from 50: 50 − 39 = 11.
10. How many more do you need to add to 28 to make 30?
2
Subtract 28 from 30: 30 − 28 = 2.
11. How many more do you need to add to 15 to make 100?
85
Subtract 15 from 100: 100 − 15 = 85.
12. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.

12 questions · Seed 104783 · 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 4 to make 50?
4 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 28 to make 100?
28 · 100 · Complements to 10, 20 & 100
3. How many more do you need to add to 13 to make 50?
13 · 50 · Complements to 10, 20 & 100
4. How many more do you need to add to 34 to make 50?
34 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 5 to make 100?
5 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
9. How many more do you need to add to 39 to make 50?
39 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 28 to make 30?
28 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 15 to make 100?
15 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104783 · 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 4 to make 50?
46
Subtract 4 from 50: 50 − 4 = 46.
2. How many more do you need to add to 28 to make 100?
72
Subtract 28 from 100: 100 − 28 = 72.
3. How many more do you need to add to 13 to make 50?
37
Subtract 13 from 50: 50 − 13 = 37.
4. How many more do you need to add to 34 to make 50?
16
Subtract 34 from 50: 50 − 34 = 16.
5. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
6. How many more do you need to add to 5 to make 100?
95
Subtract 5 from 100: 100 − 5 = 95.
7. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
8. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
9. How many more do you need to add to 39 to make 50?
11
Subtract 39 from 50: 50 − 39 = 11.
10. How many more do you need to add to 28 to make 30?
2
Subtract 28 from 30: 30 − 28 = 2.
11. How many more do you need to add to 15 to make 100?
85
Subtract 15 from 100: 100 − 15 = 85.
12. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.

12 questions · Seed 104783 · Age guidance, not curriculum certification