Thursday, October 4, 2007

Sudoku Basics: The Rules of the Game

For a different challenge, try The Greatest Maze on the Web

Sudoku Basics

The Sudoku Grid

Sudoku is a number puzzle played on a board divided into a 9x9 grid, and divided again into nine 3x3 boxes, as in Example 1A:

Empty Sudoku Grid

The Sudoku Mission

Your goal is to complete the 9x9 Sudoku grid so that each of the smaller 3x3 boxes contains every number between one and nine.

Sounds easy, huh? Take another look, Speed Racer. While completing each 3x3 box, you must also make sure that every row and every column of the 9x9 Sudoku grid also contains every number between one and nine. If you happen to be counting, you'll realize that there's only room for nine numbers in a given row or column. Nope: no room for extras or doubles.

An Empty Sudoku Puzzle

Example 1B is a reasonably simple example of what an "empty" Sudoku puzzle will look like before you get started:

Yes. The "empty" Sudoku puzzle isn't empty. Count your lucky chickens: every Sudoku puzzle begins with a gaggle of numbers already in place. In general, the easier the Sudoku puzzle, the more numbers you will find already pinned to the Sudoku grid. As the puzzles become more complicated, you will need to dig out a heavy bag of Sudoku tricks to satisfactorily complete your mission.

Take a look at the top row of Sudoku Example 1B. You begin with six of the nine numbers filled in, leaving you three numbers to identify for yourself: you still need the 4, 6 and 8 to complete the row. The first of these empty squares also sits at the top of a column. After some careful examination, you should see that this column already contains the 4 and 8. Therefore you cannot use either the 4 or 8 to fulfill the needs of your row. This, of course, lets you know how to fill that first empty square. Yes, it IS a 6. Very well done.

The Completed Sudoku Puzzle

Your job, of course, is to add numbers to the empty boxes until your Sudoku grid is full and fat, beautiful in every way. For example take a look at this (feel free not to look until you've successfully completed the puzzle yourself, as you like. I'm not the boss of you):

Learning to Solve Sudoku Puzzles

Now that you know the basic rules of Sudoku, it's time to learn how to play. First, you will need to know the smartest way to look at the puzzle board. The next step involves learning simple strategies for locating those empty boxes that are on their knees begging you for a matching number. Once you master these beginner tips, you might want to peek into the intermediate tricks of the Sudoku trade.

Ready to beat the game?
Free Sudoku Lessons

As always, Sudoku Tips and Tricks allows you to print out every Sudoku puzzle you find at our site. Every puzzle is clickable: when you click, we'll open the grid for you in a fresh, printable window. Print free and freely share with your friends. If you post one of our examples somewhere on the web, please credit Sudoku Tips and Tricks with a link on your web site.

Bag O' Tricks: Sudoku Links

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