#### How to play

The goal of Sudoku is to use login and deduction to fill all the blank squares in the grid with the correct numbers 1-9, so that each row, column and 3x3 block use each number only once.

Although Sudoku puzzles use numbers, there's no adding up or maths involved, you could even substitute the numbers for pictures if you wanted to.

#### The rules

Each su-doku puzzle only has one solution, so you need to work out which numbers go where based on the numbers already on the board. Each row, column and block must contain each of the numbers 1-9 once, and only once!

The exmple below would not be vaild, as the row contains two 8s, and no 9.

#### Using the pencil

This game features a 'pencil' tool to help you keep track of possible values for each square. This can be very useful and may in fact be required for harder puzzles when using more advanced Sudoku solving techniques. When the pencil is selcted, you can add small grey numbers to each square. Remove numbers when you see them conflicting with other numbers in the same row, column or block until only one possibility remains!

That's all there is to it! now you know everything you need - go play our free online Sudoku game and see how you get on.

If you get stuck try learning some Solving techniques to help you out!