This entertaining collection includes over 300 entertaining number-placement puzzles, arranged by five levels of difficulty. For beginners or more experienced fans alike, this beautifully designed collection will be your ideal puzzling companion. - 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.