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 25 to make 30?
25 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 46 to make 100?
46 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 82 to make 100?
82 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 21 to make 50?
21 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 15 to make 50?
15 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 38 to make 50?
38 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 29 to make 30?
29 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 22 to make 30?
22 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104771 · 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 25 to make 30?
5
Subtract 25 from 30: 30 − 25 = 5.
2. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
3. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
4. How many more do you need to add to 46 to make 100?
54
Subtract 46 from 100: 100 − 46 = 54.
5. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
6. How many more do you need to add to 82 to make 100?
18
Subtract 82 from 100: 100 − 82 = 18.
7. How many more do you need to add to 21 to make 50?
29
Subtract 21 from 50: 50 − 21 = 29.
8. How many more do you need to add to 15 to make 50?
35
Subtract 15 from 50: 50 − 15 = 35.
9. How many more do you need to add to 38 to make 50?
12
Subtract 38 from 50: 50 − 38 = 12.
10. How many more do you need to add to 29 to make 30?
1
Subtract 29 from 30: 30 − 29 = 1.
11. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
12. How many more do you need to add to 22 to make 30?
8
Subtract 22 from 30: 30 − 22 = 8.

12 questions · Seed 104771 · 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 25 to make 30?
25 · 30 · Complements to 10, 20 & 100
2. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
3. How many more do you need to add to 6 to make 20?
6 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 46 to make 100?
46 · 100 · Complements to 10, 20 & 100
5. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 82 to make 100?
82 · 100 · Complements to 10, 20 & 100
7. How many more do you need to add to 21 to make 50?
21 · 50 · Complements to 10, 20 & 100
8. How many more do you need to add to 15 to make 50?
15 · 50 · Complements to 10, 20 & 100
9. How many more do you need to add to 38 to make 50?
38 · 50 · Complements to 10, 20 & 100
10. How many more do you need to add to 29 to make 30?
29 · 30 · Complements to 10, 20 & 100
11. How many more do you need to add to 4 to make 30?
4 · 30 · Complements to 10, 20 & 100
12. How many more do you need to add to 22 to make 30?
22 · 30 · Complements to 10, 20 & 100

12 questions · Seed 104771 · 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 25 to make 30?
5
Subtract 25 from 30: 30 − 25 = 5.
2. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
3. How many more do you need to add to 6 to make 20?
14
Subtract 6 from 20: 20 − 6 = 14.
4. How many more do you need to add to 46 to make 100?
54
Subtract 46 from 100: 100 − 46 = 54.
5. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
6. How many more do you need to add to 82 to make 100?
18
Subtract 82 from 100: 100 − 82 = 18.
7. How many more do you need to add to 21 to make 50?
29
Subtract 21 from 50: 50 − 21 = 29.
8. How many more do you need to add to 15 to make 50?
35
Subtract 15 from 50: 50 − 15 = 35.
9. How many more do you need to add to 38 to make 50?
12
Subtract 38 from 50: 50 − 38 = 12.
10. How many more do you need to add to 29 to make 30?
1
Subtract 29 from 30: 30 − 29 = 1.
11. How many more do you need to add to 4 to make 30?
26
Subtract 4 from 30: 30 − 4 = 26.
12. How many more do you need to add to 22 to make 30?
8
Subtract 22 from 30: 30 − 22 = 8.

12 questions · Seed 104771 · Age guidance, not curriculum certification