Sudoku is a very popular past time for many people who love its logic based number placement. The puzzle is comprised of nine 3 by 3 squares creating one 9 by 9 square. Every row and column in the 9 by 9 square must contain the numbers 1 through 9 once and each 3 by 3 square must also contain 1 through 9 once. This book contains 50 puzzles.