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 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 82 to make 100?
82 · 100 · 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 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 21 to make 30?
21 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 27 to make 30?
27 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 8 to make 50?
8 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 48 to make 50?
48 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 22 to make 30?
22 · 30 · Complements to 10, 20 & 100
10. How many more do you need to add to 9 to make 30?
9 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 20?
2 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 28 to make 30?
28 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104759 · 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 20?
19
Subtract 1 from 20: 20 − 1 = 19.
2. How many more do you need to add to 82 to make 100?
18
Subtract 82 from 100: 100 − 82 = 18.
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 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
5. How many more do you need to add to 21 to make 30?
9
Subtract 21 from 30: 30 − 21 = 9.
6. How many more do you need to add to 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
7. How many more do you need to add to 8 to make 50?
42
Subtract 8 from 50: 50 − 8 = 42.
8. How many more do you need to add to 48 to make 50?
2
Subtract 48 from 50: 50 − 48 = 2.
9. How many more do you need to add to 22 to make 30?
8
Subtract 22 from 30: 30 − 22 = 8.
10. How many more do you need to add to 9 to make 30?
21
Subtract 9 from 30: 30 − 9 = 21.
11. How many more do you need to add to 2 to make 20?
18
Subtract 2 from 20: 20 − 2 = 18.
12. How many more do you need to add to 28 to make 30?
2
Subtract 28 from 30: 30 − 28 = 2.

12 questions · Seed 104759 · 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 20?
1 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 82 to make 100?
82 · 100 · 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 15 to make 20?
15 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 21 to make 30?
21 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 27 to make 30?
27 · 30 · Complements to 10, 20 & 100
7. How many more do you need to add to 8 to make 50?
8 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 48 to make 50?
48 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 22 to make 30?
22 · 30 · Complements to 10, 20 & 100
10. How many more do you need to add to 9 to make 30?
9 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 2 to make 20?
2 · 20 · Complements to 10, 20 & 100
12. How many more do you need to add to 28 to make 30?
28 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104759 · 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 20?
19
Subtract 1 from 20: 20 − 1 = 19.
2. How many more do you need to add to 82 to make 100?
18
Subtract 82 from 100: 100 − 82 = 18.
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 15 to make 20?
5
Subtract 15 from 20: 20 − 15 = 5.
5. How many more do you need to add to 21 to make 30?
9
Subtract 21 from 30: 30 − 21 = 9.
6. How many more do you need to add to 27 to make 30?
3
Subtract 27 from 30: 30 − 27 = 3.
7. How many more do you need to add to 8 to make 50?
42
Subtract 8 from 50: 50 − 8 = 42.
8. How many more do you need to add to 48 to make 50?
2
Subtract 48 from 50: 50 − 48 = 2.
9. How many more do you need to add to 22 to make 30?
8
Subtract 22 from 30: 30 − 22 = 8.
10. How many more do you need to add to 9 to make 30?
21
Subtract 9 from 30: 30 − 9 = 21.
11. How many more do you need to add to 2 to make 20?
18
Subtract 2 from 20: 20 − 2 = 18.
12. How many more do you need to add to 28 to make 30?
2
Subtract 28 from 30: 30 − 28 = 2.

12 questions · Seed 104759 · Age guidance, not curriculum certification