Become a master in solving Sudoku X. After solving all the puzzle in this book, you will be a Sudoku X Pro. You start with easy Sudoku X puzzle and you gradually build your way up to extremely difficult Sudoku X puzzle. Once you pick up this book, you won't be able to put it back down. You have been warned! Only 1 large print puzzle per page, with lots of white space for scribbling. Sudoku X 9x9 - Hard to Extreme is a collection of 276 puzzle: I guarantee that every logic puzzle in this Sudoku X puzzle book has been carefully checked to ensure that each puzzle has only 1 solution. None of the puzzle in this book will appear in any of the other English PuzzleBooks.net books. Sudoku X is also known as Diagonal Sudoku, Kokonotsu, Taikakusen Nanpure, Diagonal Line Number Place, Sudoku-X.