List the prime factorization of each number
Take the highest power of each prime that appears in any factorization
Multiply those highest powers together to get the LCM
If using a list method: list multiples of the largest number until a common multiple is found
If using the GCD method: use LCM(a, b) = |a·b| / GCD(a, b)
For more than two numbers: compute LCM stepwise, e.g., LCM(a, b, c) = LCM(LCM(a, b), c)