Box Brain Sudoku
Rules › Classic
How to play Classic sudoku
The sudoku everyone knows: a 9×9 grid, some digits given, and one way to fill the rest. Every other mode here builds on these rules.
The original.
The rules
- Every row, column and 3×3 box holds the digits 1 to 9 once each.
Where to start
- Look for a box missing only one or two digits, then check which rows and columns already use them.
- If a digit fits in only one cell of a row, column or box, it goes there. This is a hidden single, the most useful move in sudoku.
- If a cell has only one digit left that it could be, that is a naked single. Pencil marks make these easy to spot.
Play Classic in Box Brain Sudoku
Every Classic puzzle in the app has exactly one solution and can be solved by logic alone, from Easy to Expert. Stuck? A hint first nudges you towards the right area, then names the technique and shows the move.