Best Online Sudoku

Sudoku Basics

Make you custom with the nomenclature used in our tutorials


If you are completely new to sudoku, you will get an explanation of the simple rules for a standard sudoku containing 81 cells (9 rows x 9 columns) here. You can see all sorts of sudoku variations around, but this is the most common one and it's the one you can solve direct on this web site or print if you use the Home button in the menu above.. First we will explain the nomenclature that will be used in future published tutorials. See image 1 below.

Image 1

Image 1.

Row, Column, Box and Cell

Above in image 1 you can see that we have 9 rows, each containing 9 cells, named row 1 to row 9 from top to bottom. Every row must contain the digits 1 to 9, one digit in each cell.

We also have 9 columns, each containing 9 cells, named column 1 to column 9 from left to right. Each column must contain the digits 1 to 9, one digit in each cell.

Finally there are 9 boxes, each containing 9 cells.

The 3 top boxes are named, top left box, top center box and top right box. The 3 middle boxes are named, middle left box, middle center box and middle right box. The 3 bottom boxes are named, bottom left box, bottom center box and bottom right box. Each box must contain the digits 1 to 9, one digit in each cell.

Top left, top center, top right and middle left, middle center, middle right as well as bottom left, bottom center, bottom right are also the names of the cells within each box.

As you can see, vertically we have top, middle and bottom. Horizontally we have left, center and right.

A unique Sudoku, only one sulotion

A sudoku should only have one solution. In order to have only one solution, enough digits must be given before you start. The minimum amount of given digits in a standard sudoku ( 9 rows and 9 columns) with only one solution is 17. Sudokus with only 17 digits given are very rare. A difficult sudoku usually have 20 to 25 digits given. A easy sudoku have around 30 digits or a few more given.

We try to make it easy

In coming tutorials here, we will start very slow and easy, try to explain every move in detail. The images will look like image 2 below.

Image 2

Image 2.

The yellow background show rows and columns that already contains the figure 1. You can easily see that the digit one in the top left box only can go into one cell. The cell where we indicate the placement of digit 1, using a speech bubble. On the next image, where the digit 1 is placed in that cell, a blue font is used. It's only the given digits that have black font. The digits we place in the sudoku while solving it, are entered using a blue font.


About the author: Olov Forsgren is a retired software engineer with lifelong experience in marketing. He has been in network marketing over six years. His hobby is social media marketing and attraction marketing. His 80K+ followers on Twitter, 2,5K+ friends on Facebook and 7K+ followers on Google Plus indicates that he even master the most modern social marketing techniques.