What is the Least Common Multiple of 638 and 642?

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 638 and 642 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 638 and 642, than apply into the LCM equation.

GCF(638,642) = 2
LCM(638,642) = ( 638 × 642) / 2
LCM(638,642) = 409596 / 2
LCM(638,642) = 204798

Least Common Multiple (LCM) of 638 and 642 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 638 and 642. First we will calculate the prime factors of 638 and 642.

Prime Factorization of 638

Prime Factorization of 642

Now multiplying the highest exponent prime factors to calculate the LCM of 638 and 642.

LCM(638,642) = 2¹ × 11¹ × 29¹ × 3¹ × 107¹
LCM(638,642) = 204798