This Brain Games Sudoku book is compact, the perfect size for toting in a purse or bag, so there's always a puzzle at hand.With five levels of difficulty and 160 sudoku puzzles, there's plenty to challenge puzzlers of any level.If you get stuck or need a hint, answers are in the back of the book.4.5 x 5.875 inches.192 pages.Not only are sudoku puzzles fun and addictive, they can build logic and problem-solving skills!