No need to stop the puzzle fun with Big Book of Sudoku Volume I! Sharpen your mind and practice deductive reasoning with this second volume of sudoku puzzles for adults, including more than 540 challenges across four difficulty levels: Warm-Up, Challenging, and Tough. When you are done, test your skills on the ultimate Samurai Sudoku Puzzle--5 puzzles linked together by one central puzzle! Can you become a master samurai? Challenge accepted! 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.  LAY FLAT: Spiral-bound and paperback lays flat for ease of use at home or on the go. MAKES A GREAT GIFT: For the sudoku puzzle lover, these books make great gifts for any birthdays, stocking suffers, road trips, and more. BRAIN BUSTERS(tm): Part of the Brain Busters Puzzle Collection from Parragon & Cottage Door Press. Look for other books including word finds, crosswords, picture puzzles, and more.