Puzzle Games
How to play Sudoku
Fill a 9×9 grid so each row, column and 3×3 box contains the digits 1 through 9 exactly once.
What you need
A standard 9×9 Sudoku puzzle and pencil or a digital grid with notes
Set up the game
- Keep every printed clue fixed. Identify the nine rows, nine columns and nine 3×3 boxes; none is a separate turn order.
- This covers ordinary single-solution Sudoku, not killer, diagonal or irregular-box variants.
Playing Sudoku
- For each empty square, eliminate digits already present in its row, column and 3×3 box. A digit absent from all three is a candidate, not necessarily the answer.
- Enter a digit when it is the only candidate for a square, or when a digit can fit only one square within a row, column or box.
- Continue until all 81 squares are filled. Check every row, column and box for one copy of each digit 1–9; there is no score required to solve a standard puzzle.
Fill the last square of a row
A row contains 1, 2, 3, 4, 5, 6, 8 and 9. The only missing digit is 7. Enter 7 in the empty square if its column and 3×3 box do not already contain 7; a duplicate in either signals an earlier mistake.
A candidate is not a commitment
Suppose a square is missing 2 or 7 after checking its row and box. If its column already has a 7, only 2 remains and you can write it permanently. If neither appears in that column, keep both as notes until another placement resolves the choice.
Beginner decisions
- Pencil in candidates only where needed, then update them after every certain placement. Candidates are possibilities, not final entries.
- Scan a nearly complete box against its intersecting rows and columns before guessing.
Common rule mix-ups
- Repeating a digit in a row because it looked valid within its box alone.
- Changing a printed clue or assuming arithmetic sums are involved in ordinary Sudoku.
Questions about this game
Do I need math?
No calculation is needed. Digits are nine distinct symbols constrained by rows, columns and boxes.
Can more than one digit fit a square?
Yes during solving. Leave it unresolved and look for a forced placement elsewhere; a well-formed published puzzle has one intended solution.
Sources and edition notes
Standard 9×9 Sudoku constraints, as used in World Puzzle Federation competition booklets. Individual puzzles and variants add their own instructions.
Sources and stated format checked October 13, 2026. This records a document check, not a claim of hands-on testing.
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