Test your mental mettle with hundreds of tough but fun-to-solve puzzles and brainteasers sanctioned by Mensa, the internationally famous high- IQ society. Every day, challenge yourself with word ladders, ingenious anagram puzzles, equations, logic sequences, math riddles, unexpected twists on crosswords and word searches, and more: "Exactly 1 6 of a grade of high school seniors has handed in the final English essay. When 20 more assignments come in, 1 4 of the grade will have submitted the essay. How many students are in the grade? "Answers are on the reverse side of each page, in case the puzzle wins out.