Choose Your Challenge
Sudoku Rules
Complete the 9×9 grid so every row, column, and 3×3 box contains digits 1 through 9.
Each digit can appear only once per row, only once per column, and only once per 3×3 box.
Pre-filled numbers are your anchor points. Use logic — never guessing — to deduce the rest.
Toggle Notes mode to jot candidate digits in small corner marks inside each empty cell.
Solving Techniques
If a cell has only one possible digit left (after eliminating row, column and box conflicts), fill it in immediately.
If a digit can only go in one cell within a row, column or box — even if that cell has other candidates — place it there.
For each digit 1–9, scan which rows/columns already contain it. The intersection with its box tells you where it must go.
If all possible positions for a digit in a box lie in the same row or column, eliminate that digit from the rest of that row/column.
Write small candidate numbers in empty cells. As you solve more cells, candidates shrink — making next moves obvious.
Frequently Asked Questions
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