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:

In the expression

a$b, the $ symbol represents one of the following arithmetic operations onaandb(in the order the variables are shown): addition, subtraction, multiplication, and division. Given that it is not true thata$b=b$afor all possible values ofaandb, a pair of nonzero, non-identical values foraandbis chosen such thata$bproduces the same result, no matter which of the operations (under the given constraints) that $ represents. The nonzero value ofbthat cannot be chosen, no matter the value ofa, is

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

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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).

Trying to find where on earth “The Challenge Problem” is, I spent a week, as a result, missed the deadline. In you former design it was very handy to get it. Do you guys change the design in order to deny a solver the chance to solve the problem ?

Congratulations – your “new design”, thank you very much