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.

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Worksheet StudioPractice pack · Ages 7-9

Take your time. Show your thinking.

1. How many more do you need to add to 18 to make 50?
18 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 10 to make 50?
10 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 4 to make 100?
4 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 49 to make 100?
49 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 14 to make 20?
14 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 12 to make 50?
12 · 50 · 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 48 to make 100?
48 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 19 to make 50?
19 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 9 to make 30?
9 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 11 to make 100?
11 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104735 · 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 18 to make 50?
32
Subtract 18 from 50: 50 − 18 = 32.
2. How many more do you need to add to 10 to make 50?
40
Subtract 10 from 50: 50 − 10 = 40.
3. How many more do you need to add to 4 to make 100?
96
Subtract 4 from 100: 100 − 4 = 96.
4. How many more do you need to add to 49 to make 100?
51
Subtract 49 from 100: 100 − 49 = 51.
5. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
6. How many more do you need to add to 14 to make 20?
6
Subtract 14 from 20: 20 − 14 = 6.
7. How many more do you need to add to 12 to make 50?
38
Subtract 12 from 50: 50 − 12 = 38.
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 48 to make 100?
52
Subtract 48 from 100: 100 − 48 = 52.
10. How many more do you need to add to 19 to make 50?
31
Subtract 19 from 50: 50 − 19 = 31.
11. How many more do you need to add to 9 to make 30?
21
Subtract 9 from 30: 30 − 9 = 21.
12. How many more do you need to add to 11 to make 100?
89
Subtract 11 from 100: 100 − 11 = 89.

12 questions · Seed 104735 · 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 18 to make 50?
18 · 50 · Complements to 10, 20 & 100
2. How many more do you need to add to 10 to make 50?
10 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 4 to make 100?
4 · 100 · Complements to 10, 20 & 100
4. How many more do you need to add to 49 to make 100?
49 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 14 to make 20?
14 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 12 to make 50?
12 · 50 · 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 48 to make 100?
48 · 100 · Complements to 10, 20 & 100
10. How many more do you need to add to 19 to make 50?
19 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 9 to make 30?
9 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 11 to make 100?
11 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104735 · 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 18 to make 50?
32
Subtract 18 from 50: 50 − 18 = 32.
2. How many more do you need to add to 10 to make 50?
40
Subtract 10 from 50: 50 − 10 = 40.
3. How many more do you need to add to 4 to make 100?
96
Subtract 4 from 100: 100 − 4 = 96.
4. How many more do you need to add to 49 to make 100?
51
Subtract 49 from 100: 100 − 49 = 51.
5. How many more do you need to add to 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
6. How many more do you need to add to 14 to make 20?
6
Subtract 14 from 20: 20 − 14 = 6.
7. How many more do you need to add to 12 to make 50?
38
Subtract 12 from 50: 50 − 12 = 38.
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 48 to make 100?
52
Subtract 48 from 100: 100 − 48 = 52.
10. How many more do you need to add to 19 to make 50?
31
Subtract 19 from 50: 50 − 19 = 31.
11. How many more do you need to add to 9 to make 30?
21
Subtract 9 from 30: 30 − 9 = 21.
12. How many more do you need to add to 11 to make 100?
89
Subtract 11 from 100: 100 − 11 = 89.

12 questions · Seed 104735 · Age guidance, not curriculum certification