$$5$$ is the only multiple of $$5$$ on a die, so one of the numbers rolled must be a $$5$$. To find the probability of rolling at least one $$5$$, we can find the probability of not rolling a $$5$$ and subtract that from $$1$$, since you either roll a $$5$$ or not roll a $$5$$. The probability of not rolling a $$5$$ on either dice is $$\left( \frac{5}{6} \right)\times\left( \frac{5}{6} \right)=\frac{25}{36}$$. Therefore, the probability of rolling at least one five, and thus rolling two numbers whose product is a multiple of $$5$$, is $$1-\frac{25}{36}=\frac{11}{36}$$. 
Two dice are thrown. What is the probability that the product of the two numbers is a multiple of $$5$$? ($$2001$$ AMC $$8$$ Problem, Question \#$$ 18$$) 
1) $$\frac{1}{36}$$ 
2) $$\frac{1}{18}$$ 
3) $$\frac{1}{6}$$ 
4) $$\frac{11}{36}$$ 
5) $$\frac{1}{3}$$ 