Put your brain through it's paces with this Brain Gym Pocket Series book of 200 Very Hard Sudoku puzzles, perfect for advanced players. 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. 2 puzzles per page. 5.5" by 8.5".