Fill every cell in the 9×9 grid with a number from 1 to 9.
- →Every row must contain the numbers 1–9 exactly once.
- ↓Every column must contain the numbers 1–9 exactly once.
- ⊞Every 3×3 box must also contain the numbers 1–9 exactly once.
Tip: Use the notepad button to mark possible numbers in a cell.