What is the Least Common Multiple of 1405 and 1420?

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 1405 and 1420 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 1405 and 1420, than apply into the LCM equation.

GCF(1405,1420) = 5
LCM(1405,1420) = ( 1405 × 1420) / 5
LCM(1405,1420) = 1995100 / 5
LCM(1405,1420) = 399020

Least Common Multiple (LCM) of 1405 and 1420 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 1405 and 1420. First we will calculate the prime factors of 1405 and 1420.

Prime Factorization of 1405

Prime Factorization of 1420

Now multiplying the highest exponent prime factors to calculate the LCM of 1405 and 1420.

LCM(1405,1420) = 5¹ × 281¹ × 2² × 71¹
LCM(1405,1420) = 399020