 ## How to find the Least Common Multiple of 8 and 21?

On this page below, we'll use the Prime Factorisation, and the List of Multiples method to find out the LCM of 8 and 21.

Follow the steps below, and let's calculate the LCM of 8 and 21.

### Method 1 - Prime factorization

#### Step 1: Create a list of all the prime factors of the numbers 8 and 21:

##### Prime factors of 8

The prime factors of 8 are 2, 2 and 2. Prime factorization of 8 in exponential form is:

8 = 23

##### Prime factors of 21

The prime factors of 21 are 3 and 7. Prime factorization of 21 in exponential form is:

21 = 31x71

23, 31, 71

23x31x71=168

#### Step 4: The result:

As seen on the calculation above, we have now obtained the LCM of 8 and 21.

The Least Common Multiple of 8 and 21 is 168.

### 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 8:

8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 128, 136, 144, 152, 160, 168, 176, 184, 192

#### Multiples of 21:

21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231

LCM(8, 21) = 168