How To Solve a Sudoku Puzzle
The Rule
Fill in the puzzle so that every row, every column and every 3x3 box has numbers 1 to 9. Each number can appear only once in each row, column or box.This is a row, 9 cells wide. A filled-in row must have one of each digit. There are 9 rows in the sudoku grid, and the same applies to each of them.
This is a column, 9 cells tall. A filled-in column must have one of each digit. There are 9 columns in the sudoku grid, and the same applies to each of them.
This is a box, containing 9 cells in a 3x3 layout. A filled-in box must have one of each digit. There are 9 boxes in the sudoku grid, and the same applies to each of them.
Every sudoku puzzle starts with some numbers filled in. These can not be changed. They are your starting point and you work around them and take clues from them to get started. Every sudoku puzzle has just one correct solution.
The SudokuShark.com Sudoku Game has a highlighting feature at the bottom so you can easily reveal any set of numbers.
How to Play
Getting started
There's no specific place to start any sudoku puzzle, but a good way to get going on a Sudoku puzzle is to start identifying exact locations of numbers based on the starting sudoku grid. For example, in the sample sudoku puzzle below, look at the rows in the top three boxes.
Start with the number 1. We know there must be a 1 in each row. You can see that the second and third rows already have a 1. The first row doesn't have a 1 yet.
Then look at the boxes.
The first box has a 1 in it already, so does the second. So, we can, with absolute certainty, place a 1 in the first row in the only space available in the third box.
You can keep going with this type of basic method and place numbers accordingly. You can also do the same with columns and boxes. Most times, especially on the easier sudoku puzzles, this will allow you to get most of the numbers in there. The more of the sudoku puzzle you get filled out, the easier it gets to put in the numbers you are certain of.
Sudoku isn't about guessing and trying different numbers. Each sudoku puzzle, even the ones at level 10, will have a logic based solution. As you decipher numbers with certainty, other solutions will be triggered.
Certainty where there was Uncertainty
Some Sudoku puzzles can be solved using the basic method shown above. But often you need to use other techniques. See the example below.
We can see that the first Column already has a '2' in it and the third Row already has a '2' in it. If we are to place a '2' in the first box (top-left) we find that it can go in one of three places: Top Middle, Top Right or Middle Right. We don't have the exact placement of the '2' in the top middle box locked down yet, so no help there yet.
In the second box, we can deduce that the two has to go in either the Top Left or Top Right. How? See the '2' in the center cell of the Middle Box below? That eliminates the middle Column of the second box. The '2' in the third Row in the third Box eliminates that entire row, including the second box… still with me? See where this is going?
Because we know that a '2' HAS to be in one of those spots in the top Row, we can eliminate the other two blank spaces in the top Row, in the first Box.
Which means: now there's only one place left for the '2' to go in the first Box, which would be the Middle Right spot. See, isn't Sudoku fun once you get to know how it works?
The best way to learn is to Play Our Sudoko Game!
