Need even more puzzles to master your skill?Book 4 contains even more great puzzles, another 200 puzzles in all levels.Contained in Book 4 you will find 50 easy puzzles, 50 medium puzzles, 50 hard puzzles, and 50 very hard puzzles. Each puzzle is easy to read.In each level category each puzzle gradually increases your playing level by gradually increasing the difficulty. So whether you are looking to hone your personal Sudoku puzzle skills or to just play with family or friends this book will surely provide hours of fun while challenging your brain. There are 5 books in this Sudoku Puzzle Book All Levels Series, each book containing 200 puzzles.