The SUDOKU HELPER grid is specially designed to help eliminate possible answers, allowing you to work backwards to solve difficult puzzles. SUDOKU HELPER also keeps you organized. No more forgetting what you knew on the other side of the puzzle. It's quick, it's easy, and it really works! The book includes 160 perforated sheets, enough to get any level player over the hump and solving Sudoku like a genius. SUDOKU HELPER MASTERMIND PUZZLES contains 200 difficult Sudoku puzzles from The Puzzle Society, placed inside of the Sudoku Helper grid. Any Sudoku puzzler will immediately recognize the pure simple genius of the Helper or the most difficult of Sudoku puzzles.