Sudokus are the ever-popular number placement puzzles that can help give your brain an excellent workout. Spanning a number of difficulty levels, this collection of more than 500 puzzles is sure to keep you entertained for hours. - EXERCISE YOUR BRAIN: Give your mind a great workout as you pit your wits against these number-placement teasers. - REDUCE STRESS: Feel your stress melt away as you focus on these satisfying puzzles. - OVER 500 PUZZLES AND SOLUTIONS: This bumper book of puzzles will provide hours of entertainment.