# How To Make a Sudoku Puzzle

Although invented in the U.S. in the late 1970s, Sudoku puzzles first gained popularity in Japan.  Over the past ten years of so, these highly addictive number puzzles have become increasingly popular in the U.S., and can now be found in most newspapers, in-flight magazines, and on a number of puzzle websites.

If you enjoy solving Sudoku, you will no doubt also enjoy creating your own puzzles for your friends and family to enjoy solving.  There are a number of computer programs that can be used to create Sudoku, but it is much more challenging and fun to manually create your own, using just pencil and paper.

Sudoku is a grid containing blocks or squares into which the digits 1 to 9 are placed without repeating any digit in a block of squares or on any row (horizontal or vertical).  While the grid sizes vary, the most common is the 9 x 9, which is a grid of 9 blocks (sub-grids of 9 squares arranged in a 3 x 3 pattern).

The following instructions are for a 9 x 9 grid, but they can be applied to larger Sudoku puzzles as well.

1.  Construct a blank grid.  This consists of 9 blocks (three across, three down) with each block containing 9 squares or boxes.

2.  Fill in the grid.  Using the digits 1 to 9, fill in the grid so that no block or line has a digit appearing more than once.  Following is an example of a correctly filled-in block:

1    2   9
4    6   5

3    7   8

Take care that no digit is repeated in any horizontal or vertical row as well.  Here is an example of a correctly filled in top set of blocks:

1    9    8        5    6   7        2    3    4
5    3    7        4    2   8        9    6    1
2    4    6        3    1   9        7    8    5

3.   Remove numbers to leave blank squares for solving.  Once you have your grid completely and correctly filled in, the next step in creating your Sudoku puzzle is the selective removal of digits, leaving blank squares or boxes for solvers to fill in.  If you want your puzzle to be symmetrical, you must remove mirrored pairs of digits.  If, for example, you remove a digit from the top-right square, you must remove the mirrored digit from the bottom-left square.  After each removal, check to see whether there is only one correct solution.  Continue this process until you have removed the number of digits you desire – remembering to check and make sure there is only one correct solution.

That’s all there is to it.  You have created your first Sudoku puzzle, and now you can enjoy watching your friends puzzle over how to correctly solve it!