What is the Least Common Multiple of 1220 and 1240?

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 1220 and 1240 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 1220 and 1240, than apply into the LCM equation.

GCF(1220,1240) = 20
LCM(1220,1240) = ( 1220 × 1240) / 20
LCM(1220,1240) = 1512800 / 20
LCM(1220,1240) = 75640

Least Common Multiple (LCM) of 1220 and 1240 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 1220 and 1240. First we will calculate the prime factors of 1220 and 1240.

Prime Factorization of 1220

Prime Factorization of 1240

Now multiplying the highest exponent prime factors to calculate the LCM of 1220 and 1240.

LCM(1220,1240) = 2³ × 5¹ × 61¹ × 31¹
LCM(1220,1240) = 75640