What is the Least Common Multiple of 2 and 21?
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 (LCM) of 2 and 21 is 42.
LCM(2,21) = 42
Least Common Multiple of 2 and 21 with GCF Formula
The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 2 and 21, than apply into the LCM equation.
GCF(2,21) = 1
LCM(2,21) = ( 2 × 21) / 1
LCM(2,21) = 42 / 1
LCM(2,21) = 42
Least Common Multiple (LCM) of 2 and 21 with Primes
Least common multiple can be found by multiplying the highest exponent prime factors of 2 and 21. First we will calculate the prime factors of 2 and 21.
Prime Factorization of 2
Prime factors of 2 are 2. Prime factorization of 2 in exponential form is:
2 = 21
Prime Factorization of 21
Prime factors of 21 are 3, 7. Prime factorization of 21 in exponential form is:
21 = 31 × 71
Now multiplying the highest exponent prime factors to calculate the LCM of 2 and 21.
LCM(2,21) = 21 × 31 × 71
LCM(2,21) = 42