 ## How to find the Least Common Multiple of 20 and 28?

On this page below, we'll use the Prime Factorisation, and the List of Multiples method to find out the LCM of 20 and 28.

Follow the steps below, and let's calculate the LCM of 20 and 28.

### Method 1 - Prime factorization

#### Step 1: Create a list of all the prime factors of the numbers 20 and 28:

##### Prime factors of 20

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

20 = 22x51

##### Prime factors of 28

The prime factors of 28 are 2, 2 and 7. Prime factorization of 28 in exponential form is:

28 = 22x71

22, 51, 71

22x51x71=140

#### Step 4: The result:

As seen on the calculation above, we have now obtained the LCM of 20 and 28.

The Least Common Multiple of 20 and 28 is 140.

### 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 20:

20, 40, 60, 80, 100, 120, 140, 160, 180, 200

#### Multiples of 28:

28, 56, 84, 112, 140, 168, 196, 224

#### Therefore,

LCM(20, 28) = 140