Sudoku is a logic-based placement puzzle with an aim to enter a numerical digit from 1 through 9 in each cell of a 9X9 grid. Although the first sudoku puzzle was published in the U.S., it did not attain international popularity until 2005. Solving sudoku puzzles generally involve a combination of three processes. These include scanning, marking up and analyzing. Following is a brief guide to solving soduku.

1. Scanning: Scanning generally takes place not only at the outset but also throughout the solution and consists of two basic techniques. (a) cross-hatching involves scanning rows or columns to identify which line in a particular region may contain a certain numeral by a process of elimination. (b) counting 1-9 in regions, rows and columns to identify missing numerals. Counting based upon the last numeral discovered may speed up the search.

2. Marking Up: Once no further numerals can be discovered, sudoku players often find it necessary to mark potential numerals in blank cells. This can be done by actually writing in numerals or dots to represent potential numerals.

3. Analysis: Two main approaches to analysis include "candidate elimination” and "what if.” Candidate elimination; includes succe

ssively eliminating candidate numerals from one or more cells to leave just one choice. After each answer has been achieved, another scan may be performed, usually checking to see the effect of the contingencies. What if ; using the what if approach, a cell with only two candidate numerals is selected and a guess is made. The steps above are repeated unless a duplication is found or a cell is left with no possible candidate, in which case the alternative candidate is the solution.

Ideally, one needs to find a combination of techniques which avoids some of the drawbacks of the above elements. The counting of regions, rows and columns can feel boring. However, sudoku is a fun and engaging game that can sharpen the mind and keep one entertained for hours.

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