Organized into five levels of difficulty, Brain Games(R) Sudoku Puzzles is perfect for both seasoned puzzlers and new enthusiasts alike. Find 162 engaging puzzles in this classic collection that range from easy to expert. If you get stuck or need a hint, no need to worry: an answer key is found in the back of the book. 192 pages, spiral bound. Sudoku puzzles are not only fun and addictive, they also work to maintain good mental fitness, building logic and boosting problem solving skills!.