How to Play Sudoku

Learn the rules and start solving in minutes.

Sudoku is a number placement puzzle played on a 9×9 grid. You do not need to be good at maths — it is purely about logic and pattern recognition.

The Goal

Fill every empty cell so that each row, each column, and each of the nine 3×3 boxes contains the digits 1 through 9 exactly once.

The Three Rules

• Every row must contain the digits 1–9 with no repeats.
• Every column must contain the digits 1–9 with no repeats.
• Every 3×3 box must contain the digits 1–9 with no repeats.

How to Solve: Step by Step

Step 1 — Scan for singles

Look at each empty cell and check what digits are already present in its row, column, and box. If only one digit is missing, that is the answer. These are called naked singles and they are the most common move in easy puzzles.

Step 2 — Use pencil marks

When a cell has more than one possible digit, write all candidates in small as notes. Most Sudoku apps, including this one, have a notes mode for exactly this. As you fill in other cells, remove candidates that are no longer valid.

Step 3 — Look for hidden singles

Sometimes a digit can only go in one cell within a row, column, or box — even if that cell has several candidates written in it. Scan each unit for a digit that appears as a candidate in only one place. That is a hidden single, and it is the key technique for medium puzzles.

Step 4 — Eliminate with pairs

If two cells in the same row, column, or box both contain only the same two candidates, those digits can be removed from all other cells in that unit. This is called a naked pair and unlocks harder grids that resist the earlier steps.

Tips for Beginners

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