Hard sudoku 5
Tap a square, then type a number. 0:00
Arrow keys move, 1 to 9 fill, backspace clears, and N switches pencil marks on.
About this puzzle
A hard sudoku with 27 given numbers and exactly one solution, reachable without guessing.
- Given numbers
- 27
- Empty squares
- 54
- Difficulty
- hard
- Solutions
- Exactly one
Questions
- How hard is this sudoku?
- It gives you 27 numbers and leaves 54 squares to fill. Every puzzle here has exactly one solution and can be reached by reasoning alone, so a guess is never required.
- How do pencil marks work?
- Press Notes, then type. Candidates are written small into the corners of the square and keep their position, so a 4 always sits where a 4 goes. Press Notes again to go back to entering answers.
- Does it tell me when I am wrong?
- It marks a clash: a number that repeats in its row, column or box is provably wrong. A number that merely differs from the stored solution may be an unfinished line of reasoning, so it is left alone.
- Is there an undo?
- Yes, and it steps back through answers and pencil marks alike. Your grid and your timer are kept in this browser if you close the tab.
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