# How do you find the Least common multiple of 15, 20?

LCM = 60

#### Explanation:

Let's first find the prime factors of these two numbers:

$15 = 3 \times 5$
$20 = 2 \times 2 \times 5$

The LCM will have all the prime factors from the two numbers but we can drop replicates across the numbers we're doing this for. In this example:

From 15, we get both the 3 and the 5

From 20, we get two 2s - the 5 is already accounted for in the 5 from the 15.

The LCM is:

$2 \times 2 \times 3 \times 5 = 4 \times 15 = 60$

$15 \times 2 \times 2 = 60$
$20 \times 3 = 60$