Multiple of Abundant Number is Abundant

Theorem
Let $n$ be an abundant number.

Let $m$ be a positive integer such that $m > 1$.

Then $m n$ is abundant.

Proof
We have by definition of $\sigma$ function and abundant number that:
 * $\dfrac {\map \sigma n} n > 2$

But from Abundancy Index of Product is greater than Abundancy Index of Proper Factors:
 * $\dfrac {\map \sigma {m n} } {m n} > 2$

Hence the result by definition of abundant.