Sudoku, sometimes spelled Su Doku, is a placement puzzle, also known as Number Place in the United States. 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 subgrid

Its grid layout is reminiscent of other newspaper puzzles like crosswords and chess problems. The puzzle initially became popular in Japan in 1986 and attained international popularity in 2005. The word Sudoku means "numbers singly" in Japanese. The numer