Difference between revisions of "2010 AIME II Problems/Problem 1"

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== Problem ==
 
== Problem ==
Let <math>N</math> 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 <math>N</math> is divided by <math>1000</math>.
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Let <math>N</math> be the greatest integer multiple of <math>36</math> all of whose digits are even and no two of whose digits are the same. Find the remainder when <math>N</math> is divided by <math>1000</math>.
  
 
== Solution ==
 
== Solution ==
 
If assume to include all the even digits for the greatest integer multiple, we find that it is impossible for it to be divided by <math>3</math> or <math>36</math>.
 
If assume to include all the even digits for the greatest integer multiple, we find that it is impossible for it to be divided by <math>3</math> or <math>36</math>.
 
The next logical try would be <math>8640</math>, and this happens to be divisible by <math>36</math>. Thus <math>N = 8640 mod 1000 = \fbox{640}</math>
 
The next logical try would be <math>8640</math>, and this happens to be divisible by <math>36</math>. Thus <math>N = 8640 mod 1000 = \fbox{640}</math>

Revision as of 15:24, 1 April 2010

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