44 of the 81 cells are filled in. Look at a cell's row, column and box; when eight digits are ruled out, the ninth goes in. That is all this level asks.
New at this level
- Naked Single — Only one digit can go in this cell
All levels
- Easy · naked singles only
- Medium · up to hidden singles
- Hard · up to pairs
- Very hard · up to intersections and triples
- Expert · up to advanced techniques
- How sudoku difficulty is graded