The next installment in the popular <em>Jumbo Sudoku</em> series, <em>Jumbo Sudoku Ultimate Challenge </em>includes over 300 puzzles. The popular numerical brainteaser is a fun way to work your brain, and Sudoku fans will love this collection.<br><br><em>Jumbo Sudoku Ultimate Challenge </em>includes classic Sudoku as well as-Samurai, Kakuro, Killer, Battleship and "Son of Sudoku" Futoshiki puzzles. All the puzzles are rated on a scale of tricky to fiendish, so if you are looking to finally be challenged by Sudoku, this is the book you have been waiting for!