Let’s solve each problem step by step. We’ll find the factors of each number, then pick the common ones, and finally choose the greatest one — that’s the GCF!
---
Problem 1: Find the GCF of 8 and 12
- Factors of 8:
1, 2, 4, 8
- Factors of 12:
1, 2, 3, 4, 6, 12
- Common factors (numbers that appear in both lists):
1, 2, 4
- Greatest Common Factor (GCF):
4
---
Problem 2: Find the GCF of 15 and 20
- Factors of 15:
1, 3, 5, 15
- Factors of 20:
1, 2, 4, 5, 10, 20
- Common factors:
1, 5
- Greatest Common Factor (GCF):
5
---
Problem 3: Find the GCF of 21 and 35
- Factors of 21:
1, 3, 7, 21
- Factors of 35:
1, 5, 7, 35
- Common factors:
1, 7
- Greatest Common Factor (GCF):
7
---
Problem 4: Find the GCF of 6 and 18
- Factors of 6:
1, 2, 3, 6
- Factors of 18:
1, 2, 3, 6, 9, 18
- Common factors:
1, 2, 3, 6
- Greatest Common Factor (GCF):
6
---
Final Answer:
1. GCF of 8 and 12 is
4
2. GCF of 15 and 20 is
5
3. GCF of 21 and 35 is
7
4. GCF of 6 and 18 is
6
Parent Tip: Review the logic above to help your child master the concept of greatest common factor worksheet 3 digits.
