Test your logical thinking with this fiendish collection of expert sudoku puzzles, perfect for the more experienced puzzler. Each sudoku grid is graded by difficulty, devised by expert puzzle creator Ben Addler. Here's a collection to entertain the more experienced sudoku fan. The puzzles included have been selected to offer a challenging and satisfying solving experience. • EXERCISE YOUR BRAIN: Give your mind a great workout as you find where each missing number fits. • REDUCE STRESS: Feel your stress melt away as you focus on these satisfying puzzles. • IMPROVE YOUR SOLVING SKILL: Each puzzle is graded so you can enjoy the satisfaction of seeing your skill improve as you work through the levels. ABOUT THE SERIES: The challenges in the Ingenious Books series are created by one of the world's leading puzzle authors, Ben Addler. His wealth of experience in producing challenging puzzles ensures the dedicated puzzler a truly satisfying solving experience.