Killer Sudoku is a fun and challenging variant on classic Sudoku puzzles. To complete a puzzle you must fill the board with numbers that obey traditional Sudoku rules AND make each outlined cage shows the sum of the number within that cage. The same number cannot appear more than once in a cage. The grid is blank, but these rules give you all the information you need to solve the puzzle Volume 2 This book contains 200 Extreme puzzles, 4 per page. We are sure you will find these puzzles offer an entertaining yet effective way to exercise your brain and keep your mind sharp. All puzzles have been checked to ensure there is only one valid answer. Find more pencil puzzle books on Brainy's website www.BrainysLogicPuzzles.com