### Examples

**Example 1:** Find the HCF of 20 and 60.

**Solution:**

Factors of 20 = 1, 2, 4, 5, 10, 20.

Factors of 60 = 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60.

Take the highest common factor.

Here, 20 is the highest common factor of 20 and 60.

Therefore, HCF(20, 60) = 20.
**Example 2:** Find the HCF of 15 and 45.

**Solution:**

Factors of 15 = 1, 3, 5, 15.

Factors of 45 = 1, 3, 5, 9, 15, 45.

Take the highest common factor.

Here, 15 is the highest common factor of 15 and 45.

Therefore, HCF(15, 45) = 15.
**Example 3:** Find the HCF of 12 and 8.

**Solution:**

Factors of 12 = 1, 2, 3, 4, 6, 12.

Factors of 8 = 1, 2, 4, 8.

Take the highest common factor.

Here, 4 is the highest common factor of 12 and 8.

Therefore, HCF(12, 8) = 4.

### Exercise

**1.** HCF(24,36) = 12

**2.** HCF(18,27) = 9

**3.** HCF(48,64) = 16

**4.** HCF(45,50) = 5

**5.** HCF(12,28) = 4

**6.** HCF(120,150) = 30

**7.** HCF(18,30) = 6

**8.** HCF(30,40) = 10

**9.** HCF(56,42) = 14

**10.** HCF(27,63) = 9