2010 AIME II Problems/Problem 1

Revision as of 16:25, 1 April 2010 by Tanakeame (talk | contribs) (Solution)

Problem

Let $N$ be the greatest integer multiple of $36$ all of whose digits are even and no two of whose digits are the same. Find the remainder when $N$ is divided by $1000$.

Solution

If we include all the even digits for the greatest integer multiple, we find that it is impossible for it to be divisible by $3$, therefore by $36$ as well. The next logical try would be $8640$, which happens to be divisible by $36$. Thus $N = 8640 mod 1000 = \fbox{640}$