Learn how to take the "tease" out of brainteasers, and increase your puzzle IQ with this eye-opening guide to solving puzzles. Revealing the basic principles and strategies of cracking logic problems, it shows you, step-by-step, how to solve ten of the most common types of puzzles, from basic deduction conundrums to more complex mathematical bafflers. Packed with practice puzzles and offering hours of amusement and mental challenge, Increase Your Puzzle IQ gives you the know-how you need to decipher even the most puzzling of puzzles. Why are 1997 dollar bills worth more than 1980 dollar bills? In a box there are 20 balls, 10 white and 10 black. With a blindfold on, what is the least number you must draw out in order to get a pair of balls that matches? Which clock keeps the best time? The clock that loses a minute a day or one that doesn't run at all? I have two current U.S. coins in my hand. The two coins add up to 15?. One of the coins is not a nickel. What two coins do I have? How much dirt is there in a hole that is 1 foot wide by 1 foot long by 1 foot deep?