# Determining which weird number to use (5.6 Multiple answer problems)

I am in the beginning of preparing for the GRE, and I am wrapping up Ch 5 of the manual. I understand that the “weird” numbers are placed in order of when they should be used. In section 5.6, it decides to use –1 and –99 as second-round “weird” plug-in values. Why was –1 chosen instead of +1? I don’t see myself recognizing the need to go against the rank order of weird plug-in numbers on the official test unless I’m missing something.

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Hi @Chris3, welcome, and thanks for posting.

The weird plug-in values aren’t so much of an exact list, they’re just common values that may be useful.

In the context of this question, 1 is a “normal” value since it’s easy to plug in (e.g. 4^(1) = 4)

However, -1 is a “weird” number since taking negative exponents is weirder/harder (e.g. 4^(-1) = 0.25)

The plug-in technique is kind of a fuzzy technique to begin with; it won’t give you 100% accurate results every single time. However, it will let you answer these questions very quickly and is generally a good way to approach questions when the pure math way to solve them is more complicated.