Sudoku: Brain Games for Smart Minds Box Set is the best way to boost your deductive skills and to sharpen your memory. These books have been designed in four levels of difficulty--from simple to killer. These engaging books are the perfect means to occupy yourself when commuting long distances or just to keep oneself otherwise engaged. Each book comes with solutions at the end and the user-friendly layout of the book allows you to fill in the grids easily. Sudoku - The Ultimate Brain Workout! Perfect for all skill levels Enhances logical thinking Improves focus and memory Helps reduce stress Perfect gift for puzzle lovers