Welcome to this superb collection of 100 brand new birthday 9x9 book of sudoku puzzles. A wonderful themed book that would make a fantastic gift for that special birthday for sudoku fans! Here are the rules of 9 x 9 sudoku: - Place each number from 1 - 9 exactly once in each row, column and 3x3 bold-lined box and the grey 7 and grey 0 in the grid. All of our puzzle books are printed on very high quality paper, making the puzzle experience all the more enjoyable! For other puzzle books, visit www.puzzle-book.co.uk