How to fill a sudoku

The board is 9×9. Thick lines split it into nine boxes. Printed digits cannot be changed.

Three rules

1. Each row contains 1 to 9 once.
2. Each column contains 1 to 9 once.
3. Each box contains 1 to 9 once.

How to solve

Hints reason from the current grid only: naked and hidden singles, pairs, pointing, then chains. They mark the cell that can be deduced, and never reveal the whole puzzle.

Notes record digits you have not ruled out. When you place a digit, that note is cleared from the same row, column, and box.

Play a puzzle