FLEX YOUR brain power like never before! From acclaimed author Dr. Gary Gruber, whose proven critical-thinking methods have sold more than seven million books, this collection of mind-bending brain teasers is sure to challenge even the most experienced problem solver. Inside are logic puzzles, riddles, maddening math problems, mental games, and more! A ship is twice as old as the ship's boiler was when the ship was as old as the boiler is. The ratio of the boiler's age now to the ship's age now is what? What English word contains all the vowels, in alphabetical order? What is the three-digit number that can be made from the digits 2, 3, 5, and 7 where no two digits in the three-digit number are alike, and where the three-digit number is a multiple of each of the digits chosen? Stumped? Dr. Gruber reveals the fascinating explanations and detailed strategies for solving even the trickiest problems using his exclusive Gruber Method. DISCLAIMER: The brain teasers in this book may get you so wrapped up in critical thinking that you may not be able to do your regular work until you solve them! Any abrupt or gradual increase in creativity, intelligence, or motivation to get a better job suited to your newfound talents is strictly the reader's responsibility. For more than thirty years, Gary R. Gruber, PhD, has been recognized as a leading expert on the SAT, test-taking methods, and critical-thinking skills. His methods have been used by PBS, Sylvan Learning Centers, Grolier's Encyclopedia, and school districts throughout the country. Dr. Gruber's innovative problem-solving strategies make up the heart of the new MyMaxScore's online test prep (www.mymaxscore.com).

Solve history's greatest puzzles with this classic collection of brain teasers from The Best Brain Teasers of All Time. The best brain teasers are those that have challenged and captivated the attention of puzzle lovers throughout time. Collected here to keep your wits sharp, The Best Brain Teasers of All Time features the cleverest brain teasers from around the world and throughout history. The Best Brain Teasers of All Time gives you hours of fun-filled entertainment with brain teasers that develop your problem-solving skills in math, logic, and wordplay. Organized as an integrated challenge, these brain teasers build in momentum as they increase in difficulty from classic nursery rhymes to the riddle of the sphinx. The Best Brain Teasers of All Time puts your mind to the test with: 125 Brain Teasers that require no special skills to solve. Plus, each question comes with an optional clue in case you get stumped and a handy answer key in the back to test yourself or play with friends Brain Teasers for Every Level that cater to beginners and advanced masterminds alike, with brain teasers organized by level of difficulty to improve your skills as you move forward Hints of History that provide fun facts and background information for every brain teaser Get ready to sharpen your wit with every "aha" moment. The Best Brain Teasers of All Time is a go-to source for timeless fun and mind-blowing challenges.

Put your thinking skills to the test with fun and tricky brain teasers for kids 8 to 12 Get ready to flex your mind muscles and think outside the box with The 100 Best Brain Teasers for Kids. You'll follow Ace the alien wizard and their trusty cat Panther as you tackle puzzles and riddles that test your knowledge of wordplay, logic, and math. Will you rescue the Beloved Crystal from the mischievous Flarkspurians and bring peace to Witloo? The quest is yours to complete! 5 levels of play—Explore 100 brain teasers that get tougher as you go, so you stay sharp and improve your creative thinking skills! Clues and answers—Check the Clues section for hints from Panther if you get stuck, and check the Answer Key at the back when you think you've solved the puzzle. Crafty characters—Meet a whole cast of aliens, wizards, and animal friends as you adventure your way through word ladders, logic grids, number formulas, and more! Power up your mind with brain teasers that help you learn new skills and become an intergalactic hero!

Take your brain to the gym and give it a good workout--no pain, no...

Forever Undecided is the most challenging yet of Raymond Smullyan’s puzzle collections. It is, at the same time, an introduction—ingenious, instructive, entertaining—to Gödel’s famous theorems. With all the wit and charm that have delighted readers of his previous books, Smullyan transports us once again to that magical island where knights always tell the truth and knaves always lie. Here we meet a new and amazing array of characters, visitors to the island, seeking to determine the natives’ identities. Among them: the census-taker McGregor; a philosophical-logician in search of his flighty bird-wife, Oona; and a regiment of Reasoners (timid ones, normal ones, conceited, modest, and peculiar ones) armed with the rules of propositional logic (if X is true, then so is Y). By following the Reasoners through brain-tingling exercises and adventures—including journeys into the “other possible worlds” of Kripke semantics—even the most illogical of us come to understand Gödel’s two great theorems on incompleteness and undecidability, some of their philosophical and mathematical implications, and why we, like Gödel himself, must remain Forever Undecided!

Just as diet and exercise can help you maintain your physical strength, daily stimulation of your brain can help save your brain from deterioration. The puzzles here are varied and include memory and logic tests; anagrams, word games, and word searches; arithmetic problems and crossword puzzles of all sorts; Futoshiki, Kakuro, and Sudoku tests; and so many more. The key to stimulating your mind is variety, not difficulty, so the puzzles have been devised to be accessible for brains of all ages. From memory quizzes to math problems, there is something here for everyone.

Do you like riddles? Do you like brain teasers? Do you like puzzles? Are you a problem solver? Are you creative? Do you think outside the box? If you can answer yes to any of these questions, this book may be perfect for you. Introducing a collection of the best riddles, puzzles, and brain teasers that has been years in the making. These will challenge the way you think, introduce you to new ways to look at problems, and expand your mind. People who love riddles, puzzles, and brain teasers are familiar with the rush of the "aha!" moment, the "that's it!" moment, that "of course!" moment, the moment of clarity that you get when the lightbulb goes off and you've figured it all out. Those moments are great exercise for your mind and brain and will help to keep you mentally sharp. Even if you are new to riddles, puzzles, and brain teasers this book will be a fun and exciting read; it will help you become a better problem solver and become more comfortable with thinking outside the box. The puzzles in this book range in difficulty from light & easy to hard to very hard and will provide a challenge for even the sharpest mind. There are discrete reasoning riddles, mathematical reasoning riddles, practical reasoning riddles, and some classical logic riddles as well, along with the old school problem-solving puzzles that you might have come across in school. There is no word play, the puzzles have definite and satisfying answers, and some of them will blow your mind. In this book you will be figuring out how to cross bridges, how to escape from prison cells, how to steal rope, how to shoot cyborgs, how to transport bananas through the desert, how to figure out the color of a hat you have on, how to turn on lightbulbs, and how to save a ton of prisoners from being executed! Enjoy it! ...and remember, once you peek at the solution you will never be able to unsee it!