The Must Have Sudoku Book for 2011 contains a collection of 365 puzzles of varying difficulty. The selection of grids, ensures a daily dose of challenging mental gymnastics. All puzzles are ranked according to difficulty and are randomly distributed throughout the book. They range from quick through nasty to cruel and deadly. The book is arranged by month with an empty grid at the end of each section for scribbling & calculating. The quick puzzles will take a couple of minutes to complete, while the nasty and cruel puzzles will have you scratching your head and chewing your pencil. As for the deadly ones - don't say I didn't warn you You may end up crying for help or begging for mercy in your attempts to solve the toughest of these puzzles. The BUYSUDOKUBOOKS.COM guarantee: Often you find sudoku books with puzzles that have more than one solution. This can waste a lot of time and drain a fair amount of ones sanity when it comes to solving a puzzle. Have no fear To ensure minimum frustration, every puzzle in this book has been carefully checked and is guaranteed to have only one solution.