How to solve Sudoku step-by-step

Most people are at least a little bit familiar with the Sudoku game, but many people still don't know how to solve Sudoku puzzles. Although it might seem hard in the beginning, the principle is actually quite simple.

The objective of this game is to fill out all the spaces in the grid with the numbers 1 to 9. Each of the numbers must only appear once in every row, every column and in every cell of the 3 x 3 boxes. This requires logic and analysis, and the difficulty can vary from very easy to extremely demanding. Being a numbers game, Sudoku solving also requires a different way of thinking that, for example, a cross-word puzzle.

Once you place a number in a box, no other box in that row, column or block can have that number. So as the game progresses, the number of possible numbers in a box is reduced. Always keep a record of the possible numbers that could go in every box, as this will help you keep track of your analysis.

Solving a Sudoku puzzle could be summarized in the following steps:

1. Write down all the possible numbers that can be in each row, column or block on a piece of paper. Make a grid consisting of a 9 x 9 boxes, which has numbers from 1 to 9. And then add the recognized numbers, one at a time, to the actual Grid

2. Exclude those numbers that can't be placed in the cell because another number of the same value must go in the same column, row or block.

3. When you know which of the nine numbers should' be in the cell, you can decide what the possible numbers are. In some instances, there is only one choice left that fits. Repeat steps 2 and 3 again using that number. In another scenario, you will need to search for possible numbers that should appear once in each row, each column and each block.

4. Chances are that you might wind up with more than a single choice. If this happens, it obviously becomes more difficult to solve the Sudoku.

If you are fortunate enough then, you can select any of the numbers and go on with steps 1 and 3 again. This works well if it is an easy Sudoku, perhaps not so well if it is a harder one. Always use a soft pencil and eraser so that making changes will be easy.

5. As with step 2, remove all the numbers that cannot possibly go in the cell. This is because a recognized number of similar values should be in the same row or column since it should not be placed anywhere else in the 9 x 9 grid. For example, if two cells already have 2 or 6 and both definitely belong in the cell, other empty cells in the row or column should not contain either of these two numbers. 

6. Finally, always check the results. The added total of each block, column or row should always be 45.

In the beginning these six steps may seem a little bit confusing, but read them through carefully a few times, try out the process and solve a few Sudoku puzzles of the simpler variety and you should understand it perfectly.

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