You don't need to be a math whiz to enjoy a great sudoku puzzle! Sharpen your mind and have some fun with this great collection of sudokus, including over 540 challenges across four difficulty levels (Warm-Up, Challenging, Tough, and the ultimate Samurai Sudoku!) A must-have for all Sudoku enthusiasts. Over 500 puzzles & solutions: hours of fun and entertainment to enjoy! Variety of levels: from levels 1 to 3 increasing levels of difficulty including warm-up, challenging, and tough. When you are done, test your skills on the ultimate samurai sudoku puzzle - 5 puzzles linked together by a central puzzle! Can you become a master samurai? Lay flat: spiral-bound lays flat for ease of use at home or on the go.