Sudoku Book 400 Extra Hard Giant Puzzles

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. With a single level of difficulty, so there are no wasted puzzles. Each gigantic puzzle fills a whole letter size page and solutions are at the end of the book.