This Sudoku book is packed with the following features: 500 Easy to Hard Sudoku Puzzles Answers to every puzzle are provided. Each puzzle is guaranteed to have only one solution. Includes free bonus puzzles you can download book (Tons of Sudoku Puzzles for Adults & Seniors) Includes free bonus puzzles you can download book (Word Search With Hidden Message: 102 Puzzles for Adults and Seniors) 500 SUDOKU Puzzle Book is a collection of 500 sudoku puzzles. Part of the popular "Sudoku Puzzle Books" series, the book is designed to help keep your brain cognitively fit, flexible, and young. 500 SUDOKU Puzzle Book is sorted into three levels of difficulty (easy, medium, and hard).