Sudoku

Sudoku is a well-known puzzle based on logical placement of numbers. How to play. The goal is to place numbers from 1 to 9 in each of the empty cells in a grid of 9x9, consisting of 3x3 subgrades called regions. The puzzle contains some initial clues, which are numbers inserted into some cells, so as to allow for induction or deduction of numbers in cells that are empty.