Sudoku Doku

Sudoku; originally called Number Place, is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 sub-grids that compose the grid (also called "boxes", "blocks", "regions", or "sub-squares") contains all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a unique solution. A Sudoku is a logic-based and not a math-based puzzle. It is possible to make und solve a Sudoku puzzle with letters or even some symbols. Number puzzles sudoku appeared in newspapers in the late 19th century, when French puzzle setters began experimenting with removing numbers from magic squares. Le Siècle, a Paris daily, published a partially completed 9×9 magic square with 3×3 sub-squares on November 19, 1892. It was not a Sudoku because it contained double-digit numbers and required arithmetic rather than logic to solve, but it shared key characteristics: each row, column and sub-square added up to the same number. The real world wide popularity started in Japan in 1986 after it was published and given the name Sudoku by Nikoli. Completed puzzles sudoku are always a type of Latin square with an additional constraint on the contents of individual regions. For sudoku example, the same single integer may not appear twice in the same row, column or in any of the nine 3×3 subregions of the 9x9 playing board.