Examples
Example 1: Find the HCF of 15 and 20.
Solution:
Factors of 15: 3, 5
Factors of 20: 2, 2, 5
Common prime factors = 5
HCF: Take only common prime factors and multiply them to get the HCF.
Therefore, HCF(15, 20) = 5.
Example 2: Find the HCF of 18 and 24.
Solution:
Factors of 18: 2, 3, 3
Factors of 24: 2, 2, 2, 3
Common prime factors = 2, 3
HCF: Take only common prime factors and multiply them to get the HCF.
Therefore, HCF(18, 24) = 6.
Example 3: Find the HCF of 20 and 30.
Solution:
Factors of 20: 2, 2, 5
Factors of 30: 2, 3, 5
Common prime factors = 2, 5
HCF: Take only common prime factors and multiply them to get the HCF.
Therefore, HCF(20, 30) = 10.
Exercise
1. HCF(32,48,64) = 16
2. HCF(40,60,80) = 20
3. HCF(21,28,35) = 7
4. HCF(9,12,15) = 3
5. HCF(18,24,36) = 6
6. HCF(15,20,25,30) = 5
7. HCF(8,12) = 4
8. HCF(21,28) = 7
9. HCF(8,24,60) = 4
10. HCF(20,30,40,50) = 10