Question

What is least common multiple of 28,12,14,21?

Answer 1

Reducing the numbers to prime factors
28 = 7 * 2 * 2
12 = 3 * 2 * 2
14 = 7 * 2
21 = 7 * 3

None of the numbers have a prime number in common with the others.
So, the least common multiple would be 12