Sudoku
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To start a new puzzle, select the level from the menu on the right hand side.
To solve the puzzle:
With a mouse
- Click on an empty cell and then click on the number grid to place a number.
- Clicking on X clears the cell.
With the keyboard
- Navigate with the cursor keys and enter numbers from the keyboard to place them in the empty cell.
- Use 0 or delete to clear a cell.
To solve the puzzle, every number from 1 to 9 must appear once and once only in:
Each of the nine vertical columns
Each of the nine horizontal rows
Each of the nine 3 x 3 boxes