What is the Least Common Multiple of 1978 and 1991?

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 1978 and 1991 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 1978 and 1991, than apply into the LCM equation.

GCF(1978,1991) = 1
LCM(1978,1991) = ( 1978 × 1991) / 1
LCM(1978,1991) = 3938198 / 1
LCM(1978,1991) = 3938198

Least Common Multiple (LCM) of 1978 and 1991 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 1978 and 1991. First we will calculate the prime factors of 1978 and 1991.

Prime Factorization of 1978

Prime Factorization of 1991

Now multiplying the highest exponent prime factors to calculate the LCM of 1978 and 1991.

LCM(1978,1991) = 2¹ × 23¹ × 43¹ × 11¹ × 181¹
LCM(1978,1991) = 3938198