What is the Least Common Multiple of 20 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 20 and 18 is 180.
LCM(20,18) = 180
Least Common Multiple of 20 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 20 and 18, than apply into the LCM equation.
GCF(20,18) = 2
LCM(20,18) = ( 20 × 18) / 2
LCM(20,18) = 360 / 2
LCM(20,18) = 180
Least Common Multiple (LCM) of 20 and 18 with Primes
Least common multiple can be found by multiplying the highest exponent prime factors of 20 and 18. First we will calculate the prime factors of 20 and 18.
Prime Factorization of 20
Prime factors of 20 are 2, 5. Prime factorization of 20 in exponential form is:
20 = 22 × 51
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 20 and 18.
LCM(20,18) = 22 × 51 × 32
LCM(20,18) = 180