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.

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Worksheet StudioPractice pack · Ages 4-6

Take your time. Show your thinking.

1. How many more do you need to add to 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 3 to make 12?
3 · 12 · Complements to 10, 20 & 100
3. How many more do you need to add to 3 to make 20?
3 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 12 to make 20?
12 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 7 to make 10?
7 · 10 · Complements to 10, 20 & 100
8. How many more do you need to add to 4 to make 15?
4 · 15 · Complements to 10, 20 & 100
9. How many more do you need to add to 7 to make 15?
7 · 15 · Complements to 10, 20 & 100
10. How many more do you need to add to 5 to make 12?
5 · 12 · Complements to 10, 20 & 100
11. How many more do you need to add to 3 to make 10?
3 · 10 · Complements to 10, 20 & 100
12. How many more do you need to add to 4 to make 10?
4 · 10 · Complements to 10, 20 & 100

12 questions · Seed 104731 · 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 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
2. How many more do you need to add to 3 to make 12?
9
Subtract 3 from 12: 12 − 3 = 9.
3. How many more do you need to add to 3 to make 20?
17
Subtract 3 from 20: 20 − 3 = 17.
4. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
5. How many more do you need to add to 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.
6. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
7. How many more do you need to add to 7 to make 10?
3
Subtract 7 from 10: 10 − 7 = 3.
8. How many more do you need to add to 4 to make 15?
11
Subtract 4 from 15: 15 − 4 = 11.
9. How many more do you need to add to 7 to make 15?
8
Subtract 7 from 15: 15 − 7 = 8.
10. How many more do you need to add to 5 to make 12?
7
Subtract 5 from 12: 12 − 5 = 7.
11. How many more do you need to add to 3 to make 10?
7
Subtract 3 from 10: 10 − 3 = 7.
12. How many more do you need to add to 4 to make 10?
6
Subtract 4 from 10: 10 − 4 = 6.

12 questions · Seed 104731 · 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 18 to make 20?
18 · 20 · Complements to 10, 20 & 100
2. How many more do you need to add to 3 to make 12?
3 · 12 · Complements to 10, 20 & 100
3. How many more do you need to add to 3 to make 20?
3 · 20 · Complements to 10, 20 & 100
4. How many more do you need to add to 16 to make 20?
16 · 20 · Complements to 10, 20 & 100
5. How many more do you need to add to 12 to make 20?
12 · 20 · Complements to 10, 20 & 100
6. How many more do you need to add to 9 to make 20?
9 · 20 · Complements to 10, 20 & 100
7. How many more do you need to add to 7 to make 10?
7 · 10 · Complements to 10, 20 & 100
8. How many more do you need to add to 4 to make 15?
4 · 15 · Complements to 10, 20 & 100
9. How many more do you need to add to 7 to make 15?
7 · 15 · Complements to 10, 20 & 100
10. How many more do you need to add to 5 to make 12?
5 · 12 · Complements to 10, 20 & 100
11. How many more do you need to add to 3 to make 10?
3 · 10 · Complements to 10, 20 & 100
12. How many more do you need to add to 4 to make 10?
4 · 10 · Complements to 10, 20 & 100

12 questions · Seed 104731 · 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 18 to make 20?
2
Subtract 18 from 20: 20 − 18 = 2.
2. How many more do you need to add to 3 to make 12?
9
Subtract 3 from 12: 12 − 3 = 9.
3. How many more do you need to add to 3 to make 20?
17
Subtract 3 from 20: 20 − 3 = 17.
4. How many more do you need to add to 16 to make 20?
4
Subtract 16 from 20: 20 − 16 = 4.
5. How many more do you need to add to 12 to make 20?
8
Subtract 12 from 20: 20 − 12 = 8.
6. How many more do you need to add to 9 to make 20?
11
Subtract 9 from 20: 20 − 9 = 11.
7. How many more do you need to add to 7 to make 10?
3
Subtract 7 from 10: 10 − 7 = 3.
8. How many more do you need to add to 4 to make 15?
11
Subtract 4 from 15: 15 − 4 = 11.
9. How many more do you need to add to 7 to make 15?
8
Subtract 7 from 15: 15 − 7 = 8.
10. How many more do you need to add to 5 to make 12?
7
Subtract 5 from 12: 12 − 5 = 7.
11. How many more do you need to add to 3 to make 10?
7
Subtract 3 from 10: 10 − 3 = 7.
12. How many more do you need to add to 4 to make 10?
6
Subtract 4 from 10: 10 − 4 = 6.

12 questions · Seed 104731 · Age guidance, not curriculum certification