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 38 to make 50?
38 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 84 to make 100?
84 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 11 to make 20?
11 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 27 to make 50?
27 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 49 to make 50?
49 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 94 to make 100?
94 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 50?
2 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104745 · 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 38 to make 50?
12
Subtract 38 from 50: 50 − 38 = 12.
2. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
3. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
4. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
5. How many more do you need to add to 84 to make 100?
16
Subtract 84 from 100: 100 − 84 = 16.
6. How many more do you need to add to 11 to make 20?
9
Subtract 11 from 20: 20 − 11 = 9.
7. How many more do you need to add to 27 to make 50?
23
Subtract 27 from 50: 50 − 27 = 23.
8. How many more do you need to add to 49 to make 50?
1
Subtract 49 from 50: 50 − 49 = 1.
9. How many more do you need to add to 94 to make 100?
6
Subtract 94 from 100: 100 − 94 = 6.
10. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
11. How many more do you need to add to 2 to make 50?
48
Subtract 2 from 50: 50 − 2 = 48.
12. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.

12 questions · Seed 104745 · 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 38 to make 50?
38 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
3. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 4 to make 20?
4 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 84 to make 100?
84 · 100 · Complements to 10, 20 & 100
6. How many more do you need to add to 11 to make 20?
11 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 27 to make 50?
27 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 49 to make 50?
49 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 94 to make 100?
94 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 50?
2 · 50 · Complements to 10, 20 & 100
12. How many more do you need to add to 8 to make 20?
8 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104745 · 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 38 to make 50?
12
Subtract 38 from 50: 50 − 38 = 12.
2. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
3. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
4. How many more do you need to add to 4 to make 20?
16
Subtract 4 from 20: 20 − 4 = 16.
5. How many more do you need to add to 84 to make 100?
16
Subtract 84 from 100: 100 − 84 = 16.
6. How many more do you need to add to 11 to make 20?
9
Subtract 11 from 20: 20 − 11 = 9.
7. How many more do you need to add to 27 to make 50?
23
Subtract 27 from 50: 50 − 27 = 23.
8. How many more do you need to add to 49 to make 50?
1
Subtract 49 from 50: 50 − 49 = 1.
9. How many more do you need to add to 94 to make 100?
6
Subtract 94 from 100: 100 − 94 = 6.
10. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
11. How many more do you need to add to 2 to make 50?
48
Subtract 2 from 50: 50 − 2 = 48.
12. How many more do you need to add to 8 to make 20?
12
Subtract 8 from 20: 20 − 8 = 12.

12 questions · Seed 104745 · Age guidance, not curriculum certification