### Examples

**Example 1:** Find the HCF of 10, 15 and 20.

**Solution:**

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

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

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

Take the highest common factor.

Here, 5 is the highest common factor of 10, 15 and 20.

Therefore, HCF(10, 15, 20) = 5.
**Example 2:** Find the HCF of 16, 24 and 32.

**Solution:**

Factors of 16 = 1, 2, 4, 8, 16.

Factors of 24 = 1, 2, 3, 4, 6, 8, 12, 24.

Factors of 32 = 1, 2, 4, 8, 16, 32.

Take the highest common factor.

Here, 8 is the highest common factor of 16, 24 and 32.

Therefore, HCF(16, 24, 32) = 8.
**Example 3:** Find the HCF of 10, 20 and 30.

**Solution:**

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

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

Factors of 30 = 1, 2, 3, 5, 6, 10, 15, 30.

Take the highest common factor.

Here, 10 is the highest common factor of 10, 20 and 30.

Therefore, HCF(10, 20, 30) = 10.

### Exercise

**1.** HCF(12,18,24) = 6

**2.** HCF(8,16,24) = 8

**3.** HCF(36,48,60) = 12

**4.** HCF(24, 36, 48) = 12

**5.** HCF(15, 21, 27) = 3

**6.** HCF(18, 27, 45) = 9

**7.** HCF(24, 40, 56) = 8

**8.** HCF(36, 54, 72) = 19

**9.** HCF(32, 48, 96) = 96

**10.** HCF(24, 68, 10) = 2