Let’s solve each problem step by step. We’re looking for the
Greatest Common Factor (GCF) — that means the biggest number that divides both numbers in each pair without leaving a remainder.
We’ll go one by one:
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1. GCF(40, 55)
Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40
Factors of 55: 1, 5, 11, 55
Common factors: 1, 5 → Biggest is
5
✔ GCF = 5
---
2. GCF(33, 44)
Factors of 33: 1, 3, 11, 33
Factors of 44: 1, 2, 4, 11, 22, 44
Common factors: 1, 11 → Biggest is
11
✔ GCF = 11
---
3. GCF(30, 25)
Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Factors of 25: 1, 5, 25
Common factors: 1, 5 → Biggest is
5
✔ GCF = 5
---
4. GCF(40, 18)
Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40
Factors of 18: 1, 2, 3, 6, 9, 18
Common factors: 1, 2 → Biggest is
2
✔ GCF = 2
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5. GCF(20, 75)
Factors of 20: 1, 2, 4, 5, 10, 20
Factors of 75: 1, 3, 5, 15, 25, 75
Common factors: 1, 5 → Biggest is
5
✔ GCF = 5
---
6. GCF(12, 45)
Factors of 12: 1, 2, 3, 4, 6, 12
Factors of 45: 1, 3, 5, 9, 15, 45
Common factors: 1, 3 → Biggest is
3
✔ GCF = 3
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7. GCF(24, 9)
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Factors of 9: 1, 3, 9
Common factors: 1, 3 → Biggest is
3
✔ GCF = 3
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8. GCF(45, 20)
Factors of 45: 1, 3, 5, 9, 15, 45
Factors of 20: 1, 2, 4, 5, 10, 20
Common factors: 1, 5 → Biggest is
5
✔ GCF = 5
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9. GCF(36, 18)
Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36
Factors of 18: 1, 2, 3, 6, 9, 18
Common factors: 1, 2, 3, 6, 9, 18 → Biggest is
18
✔ GCF = 18
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10. GCF(25, 35)
Factors of 25: 1, 5, 25
Factors of 35: 1, 5, 7, 35
Common factors: 1, 5 → Biggest is
5
✔ GCF = 5
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Final Answer:
1. 5
2. 11
3. 5
4. 2
5. 5
6. 3
7. 3
8. 5
9. 18
10. 5
Parent Tip: Review the logic above to help your child master the concept of finding common factors worksheet.
