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 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 2 to make 20?
2 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 1 to make 50?
1 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 34 to make 100?
34 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 6 to make 100?
6 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 10 to make 50?
10 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 23 to make 50?
23 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 46 to make 50?
46 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 86 to make 100?
86 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 72 to make 100?
72 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104752 · 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 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
2. How many more do you need to add to 2 to make 20?
18
Subtract 2 from 20: 20 − 2 = 18.
3. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
4. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
5. How many more do you need to add to 1 to make 50?
49
Subtract 1 from 50: 50 − 1 = 49.
6. How many more do you need to add to 34 to make 100?
66
Subtract 34 from 100: 100 − 34 = 66.
7. How many more do you need to add to 6 to make 100?
94
Subtract 6 from 100: 100 − 6 = 94.
8. How many more do you need to add to 10 to make 50?
40
Subtract 10 from 50: 50 − 10 = 40.
9. How many more do you need to add to 23 to make 50?
27
Subtract 23 from 50: 50 − 23 = 27.
10. How many more do you need to add to 46 to make 50?
4
Subtract 46 from 50: 50 − 46 = 4.
11. How many more do you need to add to 86 to make 100?
14
Subtract 86 from 100: 100 − 86 = 14.
12. How many more do you need to add to 72 to make 100?
28
Subtract 72 from 100: 100 − 72 = 28.

12 questions · Seed 104752 · 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 19 to make 20?
19 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 2 to make 20?
2 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 6 to make 30?
6 · 30 · Complements to 10, 20 & 100
4. How many more do you need to add to 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 1 to make 50?
1 · 50 · Complements to 10, 20 & 100
6. How many more do you need to add to 34 to make 100?
34 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 6 to make 100?
6 · 100 · Complements to 10, 20 & 100
8. How many more do you need to add to 10 to make 50?
10 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 23 to make 50?
23 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 46 to make 50?
46 · 50 · Complements to 10, 20 & 100
11. How many more do you need to add to 86 to make 100?
86 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 72 to make 100?
72 · 100 · Complements to 10, 20 & 100

12 questions · Seed 104752 · 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 19 to make 20?
1
Subtract 19 from 20: 20 − 19 = 1.
2. How many more do you need to add to 2 to make 20?
18
Subtract 2 from 20: 20 − 2 = 18.
3. How many more do you need to add to 6 to make 30?
24
Subtract 6 from 30: 30 − 6 = 24.
4. How many more do you need to add to 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
5. How many more do you need to add to 1 to make 50?
49
Subtract 1 from 50: 50 − 1 = 49.
6. How many more do you need to add to 34 to make 100?
66
Subtract 34 from 100: 100 − 34 = 66.
7. How many more do you need to add to 6 to make 100?
94
Subtract 6 from 100: 100 − 6 = 94.
8. How many more do you need to add to 10 to make 50?
40
Subtract 10 from 50: 50 − 10 = 40.
9. How many more do you need to add to 23 to make 50?
27
Subtract 23 from 50: 50 − 23 = 27.
10. How many more do you need to add to 46 to make 50?
4
Subtract 46 from 50: 50 − 46 = 4.
11. How many more do you need to add to 86 to make 100?
14
Subtract 86 from 100: 100 − 86 = 14.
12. How many more do you need to add to 72 to make 100?
28
Subtract 72 from 100: 100 − 72 = 28.

12 questions · Seed 104752 · Age guidance, not curriculum certification