Sudoku is a very popular logic game that generally uses numbers, but requires no mathematical skills at all. Any item can be used in place of the numbers including letters or pictures, but numbers are the traditional symbol to use.
Sudoku involves arranging nine symbols so that there are no duplicate symbols in any row, column or three by three square. The entire grid is nine by nine and contains nine mini grids arranged three across and three down.
The game is started with several symbols already in place to make the game have only one solution.
Solving
To solve Sudoku, the solver must look over the existing symbols and start eliminating which symbols cannot go in the empty squares. One way to keep track of this is to use dots or tiny numbers in the empty squares.
Once all but one of the symbols is eliminated, the symbol can be permanently written in.
The first few will take a lot of time and logic to solve, but once several are in place, the pace picks up fairly quickly and soon the last symbols can be written in immediately.
This rewarding acceleration of solving is what makes the puzzle so popular and fun to solve. Sudoku puzzles difficulty can be set by which symbols are left on the grid.
Generally the less symbols to start with the harder the puzzle, but is certainly not always the case
Variations
Sudoku puzzles can have other size grids. Some can be as small as four by four or as large as 25 by 25. A common variant is a 16 by 16 puzzle with 16 four by four grids embedded.
If numbers are used in this puzzle, the extra digits are A through G. Sudoku grids can have other geometric shapes and even be three dimensional.
Some History
Sudoku looks very much like a magic square puzzle, but actually involves no adding like a magic square does. The first puzzles of this type involved adding numbers in a nine by nine grid.
Later on when only the numbers one through nine were used and only one occurrence could appear in each row and column did Sudoku type puzzles really became known.
This was when any symbol could be used in place of a number making the puzzle purely logic and very much like today's Sudoku.
Around 1980 Dell Magazine, best known for their crossword puzzles, started publishing the first true Sudoku puzzles and called them 'Number Place'.
The name was very fitting as the puzzles simply involved using logic to place numbers in the grid. Sure enough, Dell Magazine placed the puzzles in the logic section and not in the math section of their magazines.
Sudoku really started to take off in Japan in the mid 1980s when a newspaper started publishing the puzzles. This was the first occurrence of the name Sudoku.
Once computer programs could generate Sudoku puzzles of varying difficulties quickly, the puzzle really took off and by 2005 Sudoku books were all over book stores world wide.
Later computer software was sold that instantly created Sudoku puzzles and also made recording eliminated numbers easy. These programs also made correcting mistakes easy and could offer hints for the novice user and tips on how to play.
Finally, web sites started to offer the puzzle online and Sudoku became a mainstream casual game.
Sudoku is a classic example of how an easy to learn game that has been around for a while can become popular very quickly.
Happy solving.
About the Author
Timothy Sharkey works for Softgame Company, maker of
card games, video poker and puzzles. He writes articles for the
casual games web site.
