title: The World's 200 Hardest Brain Teasers: Mind-Boggling Puzzles, Problems, and Curious Questions to Sharpen Your Brain
author:  Gary Gruber 
description: <strong>Gary R. Gruber, PhD</strong>, is recognized nationally as the leading expert on the SAT, test-taking methods and critical thinking skills. His books on test taking and critical thinking skills have sold more than seven million copies.
zlib_text: ![](Images/image00062.jpeg)
  
  The World’s 200 Hardest
  
  **Brain**
  
  **Teasers**
  
  Mind-Boggling **Puzzles** ,
  
  **Problems** , and
  
  Curious **Questions** to
  
  Sharpen Your Brain
  
   **Gary r. GruBer, PhD**
  
  Copyright © 2010 by Gary R. Gruber
  
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