Greatest Common Factor (GCF) Worksheets
Find the greatest number that divides both numbers.
Greatest Common Factor (GCF)
Name:Date:Score:
Find the greatest common factor (the biggest number that divides both).
- 1GCF of 30 and 20 =
- 2GCF of 40 and 64 =
- 3GCF of 72 and 81 =
- 4GCF of 42 and 48 =
- 5GCF of 40 and 10 =
- 6GCF of 20 and 24 =
- 7GCF of 45 and 30 =
- 8GCF of 16 and 32 =
- 9GCF of 70 and 80 =
- 10GCF of 18 and 36 =
- 11GCF of 30 and 18 =
- 12GCF of 8 and 12 =
Printable Worksheets for Kids · printableworksheetsforkids.pages.dev
Greatest Common Factor (GCF)
Name:Date:Score:
Find the greatest common factor (the biggest number that divides both).
- 1GCF of 72 and 16 =
- 2GCF of 45 and 20 =
- 3GCF of 54 and 36 =
- 4GCF of 40 and 72 =
- 5GCF of 21 and 42 =
- 6GCF of 16 and 4 =
- 7GCF of 81 and 54 =
- 8GCF of 16 and 12 =
- 9GCF of 45 and 72 =
- 10GCF of 56 and 40 =
- 11GCF of 44 and 77 =
- 12GCF of 28 and 56 =
Printable Worksheets for Kids · printableworksheetsforkids.pages.dev
Greatest Common Factor (GCF)
Name:Date:Score:
Find the greatest common factor (the biggest number that divides both).
- 1GCF of 16 and 18 =
- 2GCF of 54 and 36 =
- 3GCF of 12 and 8 =
- 4GCF of 63 and 54 =
- 5GCF of 27 and 54 =
- 6GCF of 30 and 40 =
- 7GCF of 77 and 33 =
- 8GCF of 96 and 36 =
- 9GCF of 48 and 40 =
- 10GCF of 18 and 27 =
- 11GCF of 24 and 21 =
- 12GCF of 12 and 14 =
Printable Worksheets for Kids · printableworksheetsforkids.pages.dev
Answer key — Sheet A (12 answers)
- 1. 10
- 2. 8
- 3. 9
- 4. 6
- 5. 10
- 6. 4
- 7. 15
- 8. 16
- 9. 10
- 10. 18
- 11. 6
- 12. 4
Answer key — Sheet B (12 answers)
- 1. 8
- 2. 5
- 3. 18
- 4. 8
- 5. 21
- 6. 4
- 7. 27
- 8. 4
- 9. 9
- 10. 8
- 11. 11
- 12. 28
Answer key — Sheet C (12 answers)
- 1. 2
- 2. 18
- 3. 4
- 4. 9
- 5. 27
- 6. 10
- 7. 11
- 8. 12
- 9. 8
- 10. 9
- 11. 3
- 12. 2
About this skill
The GCF is used to simplify fractions: divide the top and bottom by it and the fraction is in simplest form.
How to teach it
- List factors in pairs, working from 1 upwards until the pairs meet.
- Use a factor tree for prime factorisation.
- Learn the divisibility rules for 2, 3, 5, 9 and 10 first.
Mistakes to watch for
- Missing factor pairs or listing a factor twice.
- Calling 1 a prime or treating 9 as prime.
Where to go next
- Simplifying FractionsG4, G5 · Math
- Least Common Multiple (LCM)G5, G6 · Factoring & Prime Factors
- Prime FactorizationG5, G6 · Factoring & Prime Factors
- Divisibility RulesG4, G5 · Factoring & Prime Factors
- Factors of a NumberG4 · Factoring & Prime Factors
- Prime and Composite NumbersG4, G5 · Factoring & Prime Factors
