Sudoku (Volume 85)

     Sudoku is a logic-based number placement puzzle. The objective is to fill in a 9X9 grid so that the numbers 1 through 9 occur exactly once in each row, column, and in each of the nine 3×3 boxes. The numbers can appear in any order. All Sudoku puzzles have a partially filled grid, so you can identify which numbers need to be provided on the blank boxes.
     The modern puzzle was invented by an American architect, Howard Garns, in 1979 and published by Dell Magazines under the name ‘Number Place’. It became popular in Japan in 1986, after it was published by Nikoli and given the name Sudoku, short for ‘sûji wa dokushin ni kagiru’, meaning ‘the numbers must be single’, or ‘the numbers must occur only once’.