Mr. Egghead's Sudoku 500 Extra Hard Puzzles With Solutions: Only One Level Of Difficulty Means No Wasted Puzzles

Sudoku is a fun game which helps exercise the brain and also gives you a great sense of accomplishment. It is said that it can delay dementia by making your brain work in a different way. This book contains 500 extra hard puzzles, with 4 puzzles per page and solutions at the end. 8.5" X 11"