Jigsaw Sudoku is a very interesting as well as an intellectual puzzle which develops your logical power. The object is to write numbers from 1 to 9 into the cells of the 9x9 diagram, so that each number occurs exactly once in each row, in each column, and each irregular shaped region. Volume #4 This book contains 200 Hard 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. We never duplicate a logic puzzle in any of our books. Our books are printed on high quality 60 lb paper. Find more pencil puzzle books on Brainy's website! www.BrainysLogicPuzzles.com