Let's solve each problem step by step to find the
Greatest Common Factor (GCF) of the given pairs of numbers. We'll follow the method shown in the example: list all the factors of each number, identify the common factors, and choose the greatest one.
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1) 9, 6
Factors of 9:
1, 3, 9
Factors of 6:
1, 2, 3, 6
Common factors: 1, 3
Greatest common factor: 3
✔ GCF =
3
---
2) 20, 15
Factors of 20:
1, 2, 4, 5, 10, 20
Factors of 15:
1, 3, 5, 15
Common factors: 1, 5
Greatest common factor: 5
✔ GCF =
5
---
3) 20, 28
Factors of 20:
1, 2, 4, 5, 10, 20
Factors of 28:
1, 2, 4, 7, 14, 28
Common factors: 1, 2, 4
Greatest common factor: 4
✔ GCF =
4
---
4) 18, 2
Factors of 18:
1, 2, 3, 6, 9, 18
Factors of 2:
1, 2
Common factors: 1, 2
Greatest common factor: 2
✔ GCF =
2
---
5) 42, 12
Factors of 42:
1, 2, 3, 6, 7, 14, 21, 42
Factors of 12:
1, 2, 3, 4, 6, 12
Common factors: 1, 2, 3, 6
Greatest common factor: 6
✔ GCF =
6
---
6) 22, 16
Factors of 22:
1, 2, 11, 22
Factors of 16:
1, 2, 4, 8, 16
Common factors: 1, 2
Greatest common factor: 2
✔ GCF =
2
---
7) 20, 30
Factors of 20:
1, 2, 4, 5, 10, 20
Factors of 30:
1, 2, 3, 5, 6, 10, 15, 30
Common factors: 1, 2, 5, 10
Greatest common factor: 10
✔ GCF =
10
---
8) 12, 30
Factors of 12:
1, 2, 3, 4, 6, 12
Factors of 30:
1, 2, 3, 5, 6, 10, 15, 30
Common factors: 1, 2, 3, 6
Greatest common factor: 6
✔ GCF =
6
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✔ Final Answers:
1) 9, 6 →
3
2) 20, 15 →
5
3) 20, 28 →
4
4) 18, 2 →
2
5) 42, 12 →
6
6) 22, 16 →
2
7) 20, 30 →
10
8) 12, 30 →
6
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