### GMAT Challenge Problem Showdown: August 12, 2013

We invite you to test your GMAT knowledge for a chance to win! Each week, we will post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for a free Manhattan GMAT Prep item. Tell your friends to get out their scrap paper and start solving!

Here is this week’s problem:

For how many unique pairs of nonnegative integers {a, b} is the equation

a^{2}–b^{2}= 225 true?

To see the answer choices, and to submit your answer, visit our Challenge Problem Showdown page on our site.

Discuss this week’s problem with like-minded GMAT takers on our Facebook page.

The weekly winner, drawn from among all the correct submissions, will receive One Year of Access to our Challenge Problem Archive, AND the GMAT Navigator, AND Our Six Computer Adaptive Tests ($92 value).

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