Click on the pen button, then left-click on a square and drag the cursor up and down to enter your “pen” answer. You can also type in the number. If you’re not sure of an answer, you can select the pencil button instead. Mouse over a square and click on the number(s) you want to enter.
Use simple logic to fill in the puzzle’s nine rows and nine columns with numerals 1-9. Each number can only be used once in a given row or column. Enter the correct number in every grid square to win! Sudoku has two modes: Pen and Pencil.