How to Solve a Sudoku Puzzle

Although best known as a mind-challenging Japanese import, sudoku was actually invented in 1979 by an American. Sudoku rules state that a number can only be used one time per column and row, making the puzzle challenging to solve. While traditional sudoku involves no mathematics, it does rely heavily on logic. There have been a wide variety of techniques developed that can help you solve both easy and hard puzzles.

Instructions

Difficulty: Moderately Challenging

Things You’ll Need:

• Sudoku puzzle
• Pencil

1. Glance over the puzzle for a few minutes to try to single out any spaces where only one number could possibly fit. There is usually at least one of these in every sudoku puzzle. As you fill in single numbers, keep checking over the empty boxes to see if more obvious matches pop up.
2. Use a pencil to lightly mark each cell with the numbers that could logically belong in it. Some cells will only have two or three numbers, while others will contain five or more, so you'll need to write small. This will help give you a good overview of the numbers you have to work with.
3. Carefully study the markings you made in each three-by-three box to see if any of the boxes contain only one logical number. For example, when only one of the boxes in a given 3-by-3 section contains a 2, you can logically place it there.
4. Broaden your study to each row. There may be boxes that contain only one logical number, since numbers may not be repeated in any single row or column.
5. Look for identical pairs of numbers within two boxes in the same row or column. Known as "naked pairs," these groupings mean one of the boxes must contain one of the numbers, while the other contains the other number. While you may not be able to figure out yet which number goes in which box, you can safely eliminate these two numbers from any other box in the column or row.
6. Keep repeating Steps 1 through 4 periodically throughout your game play. As the puzzle progresses and more boxes are filled in, you'll begin to spot patterns and logical moves with greater ease.

Tips & Warnings

• Choose an easy puzzle to solve if you're new to sudoku. While it may be tempting to give your brain cells a challenging workout with a more advanced puzzle, you may get unnecessarily frustrated by choosing a difficult puzzle.