What is the least common factor of 12 an 30?

Answer 1

Lots of numbers are NOT common factors. For example, 5, 7, 100...Get the greatest common factor of both numbers. All common factors are factors of this greatest common factor. Note that all of them must needs be less than or equal to the greatest common factor.

Any other number is NOT a common factor.

Answer 2

The least common factor of any set of numbers is 1.

Answer 3

Everything except 12, 24, 36 and so on.

Answer 4

Anything that isn't 1, 2, 3, 6

Answer 5

5