MathsAges 4-6

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 4-6

Take your time. Show your thinking.

1. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 8 to make 12?
8 · 12 · Complements to 10, 20 & 100
3. How many more do you need to add to 7 to make 15?
7 · 15 · Complements to 10, 20 & 100
4. How many more do you need to add to 7 to make 10?
7 · 10 · Complements to 10, 20 & 100
5. How many more do you need to add to 13 to make 15?
13 · 15 · Complements to 10, 20 & 100
6. How many more do you need to add to 5 to make 20?
5 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 1 to make 12?
1 · 12 · Complements to 10, 20 & 100
9. How many more do you need to add to 12 to make 15?
12 · 15 · Complements to 10, 20 & 100
10. How many more do you need to add to 9 to make 15?
9 · 15 · Complements to 10, 20 & 100
11. How many more do you need to add to 10 to make 12?
10 · 12 · Complements to 10, 20 & 100
12. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104788 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 4-6

Answers and reasoning. Review before teaching.

1. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
2. How many more do you need to add to 8 to make 12?
4
Subtract 8 from 12: 12 − 8 = 4.
3. How many more do you need to add to 7 to make 15?
8
Subtract 7 from 15: 15 − 7 = 8.
4. How many more do you need to add to 7 to make 10?
3
Subtract 7 from 10: 10 − 7 = 3.
5. How many more do you need to add to 13 to make 15?
2
Subtract 13 from 15: 15 − 13 = 2.
6. How many more do you need to add to 5 to make 20?
15
Subtract 5 from 20: 20 − 5 = 15.
7. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
8. How many more do you need to add to 1 to make 12?
11
Subtract 1 from 12: 12 − 1 = 11.
9. How many more do you need to add to 12 to make 15?
3
Subtract 12 from 15: 15 − 12 = 3.
10. How many more do you need to add to 9 to make 15?
6
Subtract 9 from 15: 15 − 9 = 6.
11. How many more do you need to add to 10 to make 12?
2
Subtract 10 from 12: 12 − 10 = 2.
12. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.

12 questions · Seed 104788 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 4-6

Take your time. Show your thinking.

1. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 8 to make 12?
8 · 12 · Complements to 10, 20 & 100
3. How many more do you need to add to 7 to make 15?
7 · 15 · Complements to 10, 20 & 100
4. How many more do you need to add to 7 to make 10?
7 · 10 · Complements to 10, 20 & 100
5. How many more do you need to add to 13 to make 15?
13 · 15 · Complements to 10, 20 & 100
6. How many more do you need to add to 5 to make 20?
5 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 17 to make 20?
17 · 20 · Complements to 10, 20 & 100
8. How many more do you need to add to 1 to make 12?
1 · 12 · Complements to 10, 20 & 100
9. How many more do you need to add to 12 to make 15?
12 · 15 · Complements to 10, 20 & 100
10. How many more do you need to add to 9 to make 15?
9 · 15 · Complements to 10, 20 & 100
11. How many more do you need to add to 10 to make 12?
10 · 12 · Complements to 10, 20 & 100
12. How many more do you need to add to 1 to make 20?
1 · 20 · Complements to 10, 20 & 100

12 questions · Seed 104788 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 4-6

Answers and reasoning. Review before teaching.

1. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
2. How many more do you need to add to 8 to make 12?
4
Subtract 8 from 12: 12 − 8 = 4.
3. How many more do you need to add to 7 to make 15?
8
Subtract 7 from 15: 15 − 7 = 8.
4. How many more do you need to add to 7 to make 10?
3
Subtract 7 from 10: 10 − 7 = 3.
5. How many more do you need to add to 13 to make 15?
2
Subtract 13 from 15: 15 − 13 = 2.
6. How many more do you need to add to 5 to make 20?
15
Subtract 5 from 20: 20 − 5 = 15.
7. How many more do you need to add to 17 to make 20?
3
Subtract 17 from 20: 20 − 17 = 3.
8. How many more do you need to add to 1 to make 12?
11
Subtract 1 from 12: 12 − 1 = 11.
9. How many more do you need to add to 12 to make 15?
3
Subtract 12 from 15: 15 − 12 = 3.
10. How many more do you need to add to 9 to make 15?
6
Subtract 9 from 15: 15 − 9 = 6.
11. How many more do you need to add to 10 to make 12?
2
Subtract 10 from 12: 12 − 10 = 2.
12. How many more do you need to add to 1 to make 20?
19
Subtract 1 from 20: 20 − 1 = 19.

12 questions · Seed 104788 · Age guidance, not curriculum certification