This Book Contains 400 Hard to Very Hard Difficulty Sudoku Puzzles with answers, if you are different level please check our other books. We've had your entertainment and convenience in mind when designing this book and thought about the small details which make a difference: ALL PUZZLES IN THIS BOOK ARE NEW! Wide inner margins: easy to tear out and go . Includes free bonus puzzles you can download. Our skill levels are accurate (we worked hard at this)! Larger font and better quality paper than newspapers and magazines - easy to write on without worry of bleed through. Problem levels has been expertly assessed for consistency . No wasted puzzle in this book. 2 problems per page Big and easy to read solutions at the end of the book. KEEPS YOUR MIND HEALTHY Sudoku puzzles are a proven method for keeping the mind healthy and combating Alzheimer's and Dementia. We have Very Easy, Easy, Standard, Hard, Very Hard, Extreme levels for beginners and experienced Sudoku Puzzlers. In Killer Sudoku, sub-regions have specified sums, and no number can be repeated within a region. This variant also called "Sums Sudoku", "Sums Number Place", "Samunamupure", "Kikagaku Nampure".