What is the Least Common Multiple of 640 and 644?

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 640 and 644 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 640 and 644, than apply into the LCM equation.

GCF(640,644) = 4
LCM(640,644) = ( 640 × 644) / 4
LCM(640,644) = 412160 / 4
LCM(640,644) = 103040

Least Common Multiple (LCM) of 640 and 644 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 640 and 644. First we will calculate the prime factors of 640 and 644.

Prime Factorization of 640

Prime Factorization of 644

Now multiplying the highest exponent prime factors to calculate the LCM of 640 and 644.

LCM(640,644) = 2⁷ × 5¹ × 7¹ × 23¹
LCM(640,644) = 103040