Sharpen up your mind and improve your memory by playing Sudoku every day. Sudoku stimulates your mind, increases concentration and makes you feel happy by giving you a sense of accomplishment. It is said it can also reduce the chance of developing Alzheimers. This Sudoku puzzle book contains 400 giant size puzzles with plenty of room for notations and four levels of increasing difficulty to help take your game to the next level. Each gigantic puzzle fills a whole letter size page and solutions are at the end of the book.