Game rules

In order to complete the puzzle, you must fill each cell with a number between 1 and 9, inclusive, such that no number is repeated in any row, column or 3×3 box.

In a solved sudoku, each row, column, and 3×3 box contains all the numbers 1 through 9.

Each puzzle has only one solution.

Outline of a row, a column and a 3×3 box using highlighting option.