### Examples

**Example 1:** Find the LCM of 6, 7 and 21.

**Solution:**

Prime factorization of 6: 6 = 2, 3

Prime factorization of 7: 7 = 7

Prime factorization of 21: 21 = 3, 7

Take the common factors once and remaining unique factors.

Multiply them together to get LCM.

Therefore, LCM(6, 7, 21) = 42.
**Example 2:** Find the LCM of 15, 25 and 35.

**Solution:**

Prime factorization of 15: 15 = 3, 5

Prime factorization of 25: 25 = 5, 5

Prime factorization of 35: 35 = 5, 7

Take the common factors once and remaining unique factors.

Multiply them together to get LCM.

Therefore, LCM(15, 25, 35) = 525.
**Example 3:** Find the LCM of 6, 12 and 18.

**Solution:**

Prime factorization of 6: 6 = 2, 3

Prime factorization of 12: 12 = 2, 2, 3

Prime factorization of 18: 18 = 2, 3, 3

Take the common factors once and remaining unique factors.

Multiply them together to get LCM.

Therefore, LCM(6, 12, 18) = 36.

### Exercise

**1.** LCM(12,18,24) = 72

**2.** LCM(16,24,32) = 96

**3.** LCM(15,20,30) = 60

**4.** LCM(10,12,15) = 60

**5.** LCM(3,9,18) = 18

**6.** LCM(45,60,75) = 900

**7.** LCM(18,24,60) = 360

**8.** LCM(10,18,20) = 180

**9.** LCM(10,15,75) = 150

**10.** LCM(20,30,40) = 120