# What is the Least Common Multiple of 6 and 18?

Least common multiple or lowest common denominator (lcd) can be calculated in two way; with the LCM formula calculation of greatest common factor (GCF), or multiplying the prime factors with the highest exponent factor.

Least common multiple (LCM) of 6 and 18 is 18.

LCM(6,18) = 18

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## Least Common Multiple of 6 and 18 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 6 and 18, than apply into the LCM equation.

GCF(6,18) = 6
LCM(6,18) = ( 6 × 18) / 6
LCM(6,18) = 108 / 6
LCM(6,18) = 18

## Least Common Multiple (LCM) of 6 and 18 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 6 and 18. First we will calculate the prime factors of 6 and 18.

### Prime Factorization of 6

Prime factors of 6 are 2, 3. Prime factorization of 6 in exponential form is:

6 = 21 × 31

### Prime Factorization of 18

Prime factors of 18 are 2, 3. Prime factorization of 18 in exponential form is:

18 = 21 × 32

Now multiplying the highest exponent prime factors to calculate the LCM of 6 and 18.

LCM(6,18) = 21 × 32
LCM(6,18) = 18