Sudokus are extremely satisfying and enjoyable number-placement puzzles that give our brains a great workout. This wonderful collection of over 300 puzzles is graded by level of difficulty from beginner to the experienced solver. - IMPROVE YOUR SOLVING SKILL: Each puzzle is graded, from beginner to expert, so you can enjoy the satisfaction of seeing your skill improve as you work through the levels.- 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.