How to Find the Solution for an Incomplete Sudoku Grid?

Enter all the known numbers for the Sudoku grid you want to solve, placing "." (periods) in place of each unknown number.

Submit your grid to get the complete solution or just a hint (only one number revealed at a time) to help you progress without giving away the entire puzzle.

Note: The grid input works like a text area. Press "Enter" at the end of each line to move to the next line. See an example of a grid to solve.