Sudoku is a placement puzzle. The aim of the puzzle is to enter a numeral from 1 through 9 in each cell of a grid, most frequently a 9×9 grid made up of 3×3 sub grids (called "regions"), Note that our puzzle is in this form. You are given starting numerals in some cells. Each row, column and region must contain only one instance of each numeral. Our puzzles can range from easy to very hard!