Book excerpt: When you buy this book you get an electronic version (PDF file) of the interior of this book. You can play the puzzles in this book on your mobile phone! 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 16x16 - Hard to Extreme is a collection of 276 puzzle: 108 hard Sudoku X 16x16 puzzle 108 extreme Sudoku X 16x16 puzzle 60 extra logic 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.