This Alpha Sudoku Master Series book contains 540 Puzzles (4 Puzzles per 8 1/2 x 11 page). All the Puzzles use characters instead of numbers and were generated using the Level 17 Algorithm. Replacing the numbers with characters adds a whole new challenge to the game. If you have any suggestions for improvements, please let us know at GeniusPublishing.net. There are twelve books in this Level 17 Alpha Master Series collection. We always appreciate your reviews.