Fill each row with the numbers 1 through 9
Fill each column with the numbers 1 through 9
Fill each 3×3 box with the numbers 1 through 9
Do not repeat any number within the same row
Do not repeat any number within the same column
Do not repeat any number within the same 3×3 box
Use the given numbers as fixed clues
Place numbers only where they fit all three rules
Continue until every empty cell is filled correctly