Sudoku help - How to play and complete Sudoku puzzles

The most common form of Sudoku puzzle is made up of a 9 x 9 grid. This grid is spit up into 9 sections or regions that contain 9 numbers or spaces. These regions are normally identified by a thicker line.

The Sudoku grid will be partially been filled in, so some numbers will already be there and cannot be altered.

To complete a Sudoku puzzle you need to fill in all the boxes or fields of the Sudoku only using numbers from 1 to 9, following some simple rules.

There should be only one solution to the Sudoku puzzle.

Selecting the numbers you can use

When writing or typing in a number to a specific field you must look at the row, the column and also the region that corresponds to that field.

As shown on the right, if wish to fill in the field marked with a ? then you will have to look at the row (red), the column (blue), and the region (green) to check that the number you wish to enter does not appear already.

Sudoku grid showing which row column and region to fill in

Incorrect Sudoku examples

Incorrect Sudoku row with two number ones entered

All these examples are incorrect because the number is duplicated either in the row, the column or the region.

This is why it's a good idea to pencil in possible numbers. If you do this, as you work through the Sudoku puzzle you will eliminate these, hopefully, down to only one possible number.

Remember any number you enter must not be in the same row, column or region.

Incorrect Sudoku region with two fives entered
Incorrect Sudoku column with two eights entered

If you understand these rules then your ready to play dowedo Sudoku.

For help using our online Sudoku software please read our Sudoku Help Page