What is the Least Common Multiple of 645 and 665?

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 645 and 665 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 645 and 665, than apply into the LCM equation.

GCF(645,665) = 5
LCM(645,665) = ( 645 × 665) / 5
LCM(645,665) = 428925 / 5
LCM(645,665) = 85785

Least Common Multiple (LCM) of 645 and 665 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 645 and 665. First we will calculate the prime factors of 645 and 665.

Prime Factorization of 645

Prime Factorization of 665

Now multiplying the highest exponent prime factors to calculate the LCM of 645 and 665.

LCM(645,665) = 3¹ × 5¹ × 43¹ × 7¹ × 19¹
LCM(645,665) = 85785