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 big Sudoku puzzle book contains 400 puzzles, with two levels of difficulty to help take your game to the next level. There are 4 puzzles per page and solutions are at the end of the book.