Examples
Example 1: Find the HCF of 72 and 84.
Solution:
Factors of 72 = 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72.
Factors of 84 = 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84.
Take the highest common factor.
Here, 12 is the highest common factor of 72 and 84.
Therefore, HCF(72, 84) = 12.
Example 2: Find the HCF of 18 and 24.
Solution:
Factors of 18 = 1, 2, 3, 6, 9, 18.
Factors of 24 = 1, 2, 3, 4, 6, 8, 12, 24.
Take the highest common factor.
Here, 6 is the highest common factor of 18 and 24.
Therefore, HCF(18, 24) = 6.
Example 3: Find the HCF of 25 and 75.
Solution:
Factors of 25 = 1, 5, 25.
Factors of 75 = 1, 3, 5, 15, 25, 75.
Take the highest common factor.
Here, 25 is the highest common factor of 25 and 75.
Therefore, HCF(25, 75) = 25.
Exercise
1. HCF(18,27) = 9
2. HCF(45,60) = 15
3. HCF(32,48) = 16
4. HCF(24,36) = 12
5. HCF(60,75) = 15
6. HCF(36,42) = 6
7. HCF(16,32) = 16
8. HCF(16,20) = 4
9. HCF(19,25) = 1
10. HCF(75,80) = 5