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 21 to make 30?
21 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 6 to make 50?
6 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 1 to make 30?
1 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 25 to make 30?
25 · 30 · Complements to 10, 20 & 100
8. How many more do you need to add to 45 to make 50?
45 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 28 to make 30?
28 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 85 to make 100?
85 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 48 to make 50?
48 · 50 · Complements to 10, 20 & 100

12 questions · Seed 104766 · 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 21 to make 30?
9
Subtract 21 from 30: 30 − 21 = 9.
2. How many more do you need to add to 6 to make 50?
44
Subtract 6 from 50: 50 − 6 = 44.
3. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
4. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
5. How many more do you need to add to 1 to make 30?
29
Subtract 1 from 30: 30 − 1 = 29.
6. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
7. How many more do you need to add to 25 to make 30?
5
Subtract 25 from 30: 30 − 25 = 5.
8. How many more do you need to add to 45 to make 50?
5
Subtract 45 from 50: 50 − 45 = 5.
9. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
10. How many more do you need to add to 28 to make 30?
2
Subtract 28 from 30: 30 − 28 = 2.
11. How many more do you need to add to 85 to make 100?
15
Subtract 85 from 100: 100 − 85 = 15.
12. How many more do you need to add to 48 to make 50?
2
Subtract 48 from 50: 50 − 48 = 2.

12 questions · Seed 104766 · 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 21 to make 30?
21 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 6 to make 50?
6 · 50 · Complements to 10, 20 & 100
3. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 1 to make 30?
1 · 30 · Complements to 10, 20 & 100
6. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 25 to make 30?
25 · 30 · Complements to 10, 20 & 100
8. How many more do you need to add to 45 to make 50?
45 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 13 to make 20?
13 · 20 · Complements to 10, 20 & 100
10. How many more do you need to add to 28 to make 30?
28 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 85 to make 100?
85 · 100 · Complements to 10, 20 & 100
12. How many more do you need to add to 48 to make 50?
48 · 50 · Complements to 10, 20 & 100

12 questions · Seed 104766 · 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 21 to make 30?
9
Subtract 21 from 30: 30 − 21 = 9.
2. How many more do you need to add to 6 to make 50?
44
Subtract 6 from 50: 50 − 6 = 44.
3. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.
4. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
5. How many more do you need to add to 1 to make 30?
29
Subtract 1 from 30: 30 − 1 = 29.
6. How many more do you need to add to 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
7. How many more do you need to add to 25 to make 30?
5
Subtract 25 from 30: 30 − 25 = 5.
8. How many more do you need to add to 45 to make 50?
5
Subtract 45 from 50: 50 − 45 = 5.
9. How many more do you need to add to 13 to make 20?
7
Subtract 13 from 20: 20 − 13 = 7.
10. How many more do you need to add to 28 to make 30?
2
Subtract 28 from 30: 30 − 28 = 2.
11. How many more do you need to add to 85 to make 100?
15
Subtract 85 from 100: 100 − 85 = 15.
12. How many more do you need to add to 48 to make 50?
2
Subtract 48 from 50: 50 − 48 = 2.

12 questions · Seed 104766 · Age guidance, not curriculum certification