How to play Sudoku: a calm place to begin

The whole idea

A Classic Sudoku has nine rows, nine columns, and nine smaller 3 × 3 boxes. Fill the empty squares with the digits 1 through 9. Each digit appears once in every row, column, and box. The starting numbers are fixed: build around them.

Sudoku is a logic puzzle. You do not need arithmetic for Classic grids. A good puzzle has exactly one solution. Every puzzle on royalsudoku.com is checked for uniqueness before it reaches you.

Start with what you can see

Pick a row with several starting numbers. Which digits are missing? For each empty square, look at its column and its box. A digit already present in either cannot go in that square. Sometimes only one possibility remains.

• Scan one row, column, or box at a time.
• Look for a square with only one possible digit.
• Revisit nearby squares after every placement.

Avoid placing a digit simply because it looks plausible. Make a move when you can explain why it belongs there.

Pencil notes are your memory

Use Notes to record possible digits in an empty square. These notes are yours to maintain; they do not update automatically. Remove a possibility when a new placement rules it out. Keep notes small and deliberate so the grid stays readable.

Choose a comfortable pace

Easy is a useful starting point. Move to Medium when scanning feels natural. Hard introduces combinations of possibilities; Expert can demand techniques beyond singles, locked candidates, and pairs.

The timer is a record, not a deadline. You can spend as much time as you like on a puzzle. Your current grid saves in your browser, so a refresh preserves your progress.

Your first grid

Start an Easy puzzle, use the arrow keys to move, and type a digit to place it. Press N for notes and Delete to erase a square. Undo is there when you need it. A quiet, careful move is a good move.