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 1 to make 50?
1 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 13 to make 50?
13 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 19 to make 30?
19 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 27 to make 50?
27 · 50 · Complements to 10, 20 & 100
7. How many more do you need to add to 9 to make 50?
9 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
9. How many more do you need to add to 9 to make 30?
9 · 30 · Complements to 10, 20 & 100
10. How many more do you need to add to 11 to make 100?
11 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 20 to make 50?
20 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 19 to make 50?
19 · 50 · Complements to 10, 20 & 100

12 questions · Seed 104763 · 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 1 to make 50?
49
Subtract 1 from 50: 50 − 1 = 49.
2. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
3. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
4. How many more do you need to add to 13 to make 50?
37
Subtract 13 from 50: 50 − 13 = 37.
5. How many more do you need to add to 19 to make 30?
11
Subtract 19 from 30: 30 − 19 = 11.
6. How many more do you need to add to 27 to make 50?
23
Subtract 27 from 50: 50 − 27 = 23.
7. How many more do you need to add to 9 to make 50?
41
Subtract 9 from 50: 50 − 9 = 41.
8. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
9. How many more do you need to add to 9 to make 30?
21
Subtract 9 from 30: 30 − 9 = 21.
10. How many more do you need to add to 11 to make 100?
89
Subtract 11 from 100: 100 − 11 = 89.
11. How many more do you need to add to 20 to make 50?
30
Subtract 20 from 50: 50 − 20 = 30.
12. How many more do you need to add to 19 to make 50?
31
Subtract 19 from 50: 50 − 19 = 31.

12 questions · Seed 104763 · 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 1 to make 50?
1 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 13 to make 50?
13 · 50 · Complements to 10, 20 & 100
5. How many more do you need to add to 19 to make 30?
19 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 27 to make 50?
27 · 50 · Complements to 10, 20 & 100
7. How many more do you need to add to 9 to make 50?
9 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
9. How many more do you need to add to 9 to make 30?
9 · 30 · Complements to 10, 20 & 100
10. How many more do you need to add to 11 to make 100?
11 · 100 · Complements to 10, 20 & 100
11. How many more do you need to add to 20 to make 50?
20 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 19 to make 50?
19 · 50 · Complements to 10, 20 & 100

12 questions · Seed 104763 · 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 1 to make 50?
49
Subtract 1 from 50: 50 − 1 = 49.
2. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.
3. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
4. How many more do you need to add to 13 to make 50?
37
Subtract 13 from 50: 50 − 13 = 37.
5. How many more do you need to add to 19 to make 30?
11
Subtract 19 from 30: 30 − 19 = 11.
6. How many more do you need to add to 27 to make 50?
23
Subtract 27 from 50: 50 − 27 = 23.
7. How many more do you need to add to 9 to make 50?
41
Subtract 9 from 50: 50 − 9 = 41.
8. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
9. How many more do you need to add to 9 to make 30?
21
Subtract 9 from 30: 30 − 9 = 21.
10. How many more do you need to add to 11 to make 100?
89
Subtract 11 from 100: 100 − 11 = 89.
11. How many more do you need to add to 20 to make 50?
30
Subtract 20 from 50: 50 − 20 = 30.
12. How many more do you need to add to 19 to make 50?
31
Subtract 19 from 50: 50 − 19 = 31.

12 questions · Seed 104763 · Age guidance, not curriculum certification