### Examples

**Example 1:** Find the HCF of 12, 30 and 72.

**Solution:**

Factors of 12: 2, 2, 3

Factors of 30: 2, 3, 5

Factors of 72: 2, 2, 2, 3, 3

Common prime factors = 2, 3

HCF: Take only common prime factors and multiply them to get the HCF.

Therefore, HCF(12, 30, 72) = 6.
**Example 2:** Find the HCF of 50, 65 and 80.

**Solution:**

Factors of 50: 2, 5, 5

Factors of 65: 5, 13

Factors of 80: 2, 2, 2, 2, 5

Common prime factors = 5

HCF: Take only common prime factors and multiply them to get the HCF.

Therefore, HCF(50, 65, 80) = 5.
**Example 3:** Find the HCF of 36, 54 and 72.

**Solution:**

Factors of 36: 2, 2, 3, 3

Factors of 54: 2, 3, 3, 3

Factors of 72: 2, 2, 2, 3, 3

Common prime factors = 2, 3, 3

HCF: Take only common prime factors and multiply them to get the HCF.

Therefore, HCF(36, 54, 72) = 19.

### Exercise

**1.** HCF(32,48,64) = 16

**2.** HCF(63,84,105) = 21

**3.** HCF(45,63,81) = 9

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

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

**6.** HCF(16, 24, 32) = 8

**7.** HCF(20, 40, 60) = 20

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

**9.** HCF(27, 45, 72) = 9

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