The Little Book of Sudoku 4 contains over 200 brand new puzzles, commissioned especially for this book and created by an expert in logic and artificial intelligence. The puzzles will test experts and train those unfamiliar with Sudoku, helping to build your logic and reasoning skills, improve your memory and keep your brain healthy and young by giving it a regular workout. The perfect companion for the work commute, holidays and rainy afternoons, The Little Book of Sudoku Volume 4 will keep anyone's mind busy, but beware, as thousands of people have found, it's highly addictive!­