To clear the puzzle, click on 

Enter your puzzle here, then click on 
This will copy your puzzle into the grid below.

There are a few puzzles ready to try. Click a button to load one of them instead of writing your own.
  
  
  
  


The first step is to check each box in turn to see what could be in it. To do this, click each box and the possible values will be checked.

Next, go through each box in turn and mark those which now have only one possible number. To do this, click   Newly marked singles will be on a light green background and those previously marked as single will be on a darker green.

Having marked the new singles, for each in turn - knock it out of its row, column and box. Click on each newly marked number to do this.

Now go back to mark the new single values, and keep repeating this until no new single values are marked.

Is the puzzle is complete? If not, then what are you going to do next?

Alternatively you can do  up to marking the new singles.

Or even do the  in one go.

for boxes where there is only one possible value.

that everything is OK so far.