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## Official Guide Explanation:Problem Solving #15

Background

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Review (12th ed.). Click the links on the question number, difficulty level, and categories to find explanations for other problems.

These are the same explanations that are featured in my "Guides to the Official Guide" PDF booklets. However, because of the limitations of HTML and cross-browser compatibility, some mathematical concepts, such as fractions and roots, do not display as clearly online.

Question: 15
Page: 154
Difficulty: 4 (Moderately Easy)
Category 1: Arithmetic > Decimals >
Category 2: Arithmetic > Powers and Roots of Numbers > Powers

Explanation: It may be easier to think about this problem (and avoid careless mistakes) by using fractional equivalents. 0.1 = (1/10), (0.1)2 = ((1/10))2 = (1/100), and (0.1)3 = ((1/10))3 = (1/1000). Depending on your comfort with decimals, you may prefer to switch back to decimals from those three fractions; otherwise, find a common denominator as follows: (1/10) + (1/100) + (1/1000) = (100/1000) + (10/1000) + (1/1000) = (111/1000) = 0.111, choice (B).

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