# Practice GMAT Problem Solving Question

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Correct Answer:

**B**- In working the problem, it is extremely important to remember that, by the rules of exponents, x
^{Y}= 1/(x^{-Y})

- Alternatively, you could do the problem like this:
- Plug in 1 for n to yield (.1*1)
^{798}/(.1*1)^{800}, which is (.1)^{798}/(.1)^{800}since any number multiplied by 1 is simply that number. In other words, .1*1 = .1 - Cancel 798 0.1's from the numerator and denominator. It helps to think of the expression as x
^{798}/x^{800}, where x=0.1. This yields 1/x^{2}, or 1/(.1)^{2}. - 0.1 = 1/10, so (.1)
^{2}=1^{2}/10^{2}, or 1/100. - The number we are interested in is the reciprocal of (.1)
^{2}, that is 1/(.1)^{2}, so the reciprocal of 1/100 is 100. The answer is B.

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