Take a refreshing break with this compact, portable collection of sudoku puzzles! Includes 216 classic sudoku puzzles . - Puzzles are organized into 5 levels of difficulty , from easiest (Level 1) to hardest (Level 5).  - Complete answer key is found at the back of the book. - Spiral bound , 256 pages. Keep your mind fit and focused while having fun! Publications International, Ltd. (​PIL)  publishes books and products for kids and adults in many categories: reference, leisure, inspirational, automotive, sports, cookbooks, stationery (New Seasons), interactive and early learning (Little Grasshopper Books).