 ## How to find the Least Common Multiple of 15 and 20?

On this page below, we'll use the Prime Factorisation, and the List of Multiples method to find out the LCM of 15 and 20.

Follow the steps below, and let's calculate the LCM of 15 and 20.

### Method 1 - Prime factorization

#### Step 1: Create a list of all the prime factors of the numbers 15 and 20:

##### Prime factors of 15

The prime factors of 15 are 3 and 5. Prime factorization of 15 in exponential form is:

15 = 31x51

##### Prime factors of 20

The prime factors of 20 are 2, 2 and 5. Prime factorization of 20 in exponential form is:

20 = 22x51

31, 51, 22

31x51x22=60

#### Step 4: The result:

As seen on the calculation above, we have now obtained the LCM of 15 and 20.

The Least Common Multiple of 15 and 20 is 60.

### Method 2 - List of Multiples

Find and list multiples of each number until the first common multiple is found. This is the lowest common multiple.

#### Multiples of 15:

15, 30, 45, 60, 75, 90, 105

#### Multiples of 20:

20, 40, 60, 80, 100, 120

LCM(15, 20) = 60