Click on any empty grid square to select it. The square will turn yellow and buttons 1-9 will appear
Click on a button to put the correct number in the yellow square.
If the button turns red -
- You have selected the wrong number
- Either click another number button or choose another grid square.
 
The rules of Sudoko are as follows:-
- Every square must contain a number between one and nine
- You cannot use the same number twice in any of the marked 3x3 squares
- You cannot use the same number twice on any horizontal line
- You cannot use the same number twice on any vertical line