Puzzle
#0
Type 1–9 to fill · Space toggles pencil · Backspace clears
Arrow keys move
Fill the grid so that every row, every column and every 3 × 3 box contains the digits 1 to 9 exactly once. No arithmetic is involved and every puzzle has one solution, reachable by logic alone.
Each of the nine horizontal rows holds every digit once. A repeat anywhere in the row is a mistake.
The same rule runs vertically. Reading a column top to bottom should give you all nine digits.
The nine heavy-bordered 3 × 3 boxes follow the rule too. Most deductions come from these.
One empty cell has just one candidate left after eliminating its row, column and box. Write it in.
A digit fits in only one cell of a row, column or box, even though that cell has other candidates too.
If a digit in a box is confined to one row, it can be struck from the rest of that row outside the box.
| 1 – 9 | Enter a digit in the selected cell |
| Space | Toggle pencil marks |
| Backspace | Clear the cell |
| Arrows | Move the selection |
| Ctrl / ⌘ + Z | Undo |
Flag a digit the moment it conflicts with another.
Tint the row, column and box of the selected cell.
Clear candidates automatically when a digit rules them out.
Show elapsed time while you play.
The level a new puzzle opens at.
Scale the grid for smaller screens or weaker eyes.