What is the Least Common Multiple of 840 and 855?

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 of 840 and 855 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 840 and 855, than apply into the LCM equation.

GCF(840,855) = 15
LCM(840,855) = ( 840 × 855) / 15
LCM(840,855) = 718200 / 15
LCM(840,855) = 47880

Least Common Multiple (LCM) of 840 and 855 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 840 and 855. First we will calculate the prime factors of 840 and 855.

Prime Factorization of 840

Prime Factorization of 855

Now multiplying the highest exponent prime factors to calculate the LCM of 840 and 855.

LCM(840,855) = 2³ × 3² × 5¹ × 7¹ × 19¹
LCM(840,855) = 47880