Sudoku

Goal

Fill the 9×9 grid with the numbers 1 to 9 so that every row, every column and every 3×3 box contains all nine numbers with no repeats. Bold numbers are part of the puzzle and cannot be changed. Every puzzle has exactly one solution, so you can always solve it by logic — no guessing needed.

You may make up to 3 mistakes; wrong numbers are shown in red. Your record is your fastest time, kept separately for Easy, Medium and Hard. The current puzzle is saved automatically.

Controls

• Phone: tap an empty cell, then tap a number on the keypad below. Use Notes to pencil in small candidates and Erase to clear a cell.
• Computer: click a cell or move with the arrow keys, type 1–9, press Backspace/Delete to erase and N to toggle notes.

Tips

• Start with the number that already appears most often — it usually has very few places left.
• Selecting a cell highlights every matching number, so you can see which rows and columns already have it.
• On Hard, write notes for each cell and eliminate candidates step by step.