I think the definition of a multiple of a number is: If A is a multiple of B then it's possible to represent A as A= B* X, where X is an Integer. (A and B are also integers)
Since X must be an integer the division of A/B (X =A/B) must be an integer, otherwise A is not multiple of B.
If the division A/B is NOT an integer then A is NOT multiple of B.
Is this true?
I know that if the remainder of a number by another number is equal to 0 then they are multiple. But I'm not interested in that way to know if two numbers are multiple of each other.