Fill each row with the numbers 1 to 9 without repeats
Fill each column with the numbers 1 to 9 without repeats
Fill each 3×3 box with the numbers 1 to 9 without repeats
Use the given numbers as fixed clues
Find numbers that can fit in only one cell in a row, column, or box
Eliminate impossible numbers from each empty cell
Check rows, columns, and boxes repeatedly for missing numbers
Use overlapping constraints between rows, columns, and boxes
Continue until every cell is filled correctly