The LCM is the smallest common multiple of two or more numbers. For example, the LCM of 2 and 5 is 10. The least common factor is the smallest common factor of two or more numbers. The smallest factor of every number is 1.
common multiple is a number that is a multiple of two or more numbers. The common multiples of 3 and 4 are 0, 12, 24, ....
The least common multiple (LCM) of two numbers is the smallest number (not zero) that is a multiple of both.
So here LCM is 12.