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

The name Sudoku is the Japanese abbreviation of a longer phrase, "Suji wa dokushin ni kagiru," meaning "The digits must remain single."

The aim of the puzzle is to enter a number from 1 through 9 in each cell of a grid, most frequently a 9x9 grid made up of 3x3 subgrids (called "regions"), starting with various numbers given in some cells (the "givens").

Each row, column and region must contain only one instance of each number.

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SUDUKO LINKS

• N.Y. Times Sudoku
• Wikipedia