Sudoku Rules — How to Play and Solve

Sudoku is a logic puzzle played on a 9×9 grid divided into nine 3×3 boxes. The goal is to fill every cell with a digit from 1 to 9 so that no digit repeats in any row, column, or 3×3 box.

The grid starts with a few pre-filled numbers called "givens" or "clues". You cannot change them — they're the starting constraints that lead to a single unique solution.

The Three Rules of Sudoku

  1. Each row must contain all digits from 1 to 9 with no repeats.
  2. Each column must contain all digits from 1 to 9 with no repeats.
  3. Each of the nine 3×3 boxes must contain all digits from 1 to 9 with no repeats.

How to Play Sudoku

  1. 1
    Pick a difficulty. Kids, Easy, Medium, Hard, or Master. Pick a level that matches your experience.
  2. 2
    Select a cell. Click or tap an empty cell to highlight it.
  3. 3
    Enter a digit. Type a number from 1 to 9 on your keyboard or use the number pad.
  4. 4
    Use hints if stuck. The Hint button fills in one correct cell so you can unblock.
  5. 5
    Finish the grid. When every cell is correctly filled, the puzzle announces "Solved".

Solving Strategies

Naked Singles

Scan each empty cell: if only one digit is legal (no conflicts in row/column/box), place it.

Hidden Singles

For a given digit in a row, column, or box: if only one empty cell can hold it, place it there.

Naked Pairs

If two cells in a row, column, or box can only hold the same two digits, those digits cannot appear in any other cell of that unit.

Tips for Beginners

  • Start by scanning rows, columns and boxes that are already mostly filled — these give the easiest wins.
  • Work on digits one at a time. Pick a digit and see where it must go across the grid.
  • Use the hint button sparingly. Getting unstuck through your own reasoning is what makes sudoku satisfying.
  • If you're guessing, stop. Sudoku has a unique solution; every step should be a logical deduction.

Frequently Asked Questions

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