What is the Least Common Multiple of 4 and 5?
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 4 and 5 is 20.
LCM(4,5) = 20
Least Common Multiple of 4 and 5 with GCF Formula
The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 4 and 5, than apply into the LCM equation.
GCF(4,5) = 1
LCM(4,5) = ( 4 × 5) / 1
LCM(4,5) = 20 / 1
LCM(4,5) = 20
Least Common Multiple (LCM) of 4 and 5 with Primes
Least common multiple can be found by multiplying the highest exponent prime factors of 4 and 5. First we will calculate the prime factors of 4 and 5.
Prime Factorization of 4
Prime factors of 4 are 2. Prime factorization of 4 in exponential form is:
4 = 22
Prime Factorization of 5
Prime factors of 5 are 5. Prime factorization of 5 in exponential form is:
5 = 51
Now multiplying the highest exponent prime factors to calculate the LCM of 4 and 5.
LCM(4,5) = 22 × 51
LCM(4,5) = 20