Put your brain through it's paces with this Brain Gym book of 500 Sudoku puzzles, containing 250 hard difficulty and 250 very hard. We exercise our bodies but our brains need a workout too! Sudoku helps keep your brain healthy and functioning well. Challenge yourself to finish all the puzzles without cheating! This book contains solutions to all the puzzles. 178 pages, 4 puzzles per page. 8.5 by 11".