Sudoku Rules and How to Play

The game of Sudoku is played on a 9 by 9 grid. The game board consists of 9 rows, 9 columns and 9 blocks, called "regions".

In the image above, the one row is highlighted in green, one column is highlighted in light blue, and one region is highlighted in yellow. The black numbers represent numbers that are provided at the start of the puzzle. You must fill in the empty squares with the correct numbers.

In the finished puzzle above, the numbers in blue represent the numbers that we've used in order to completed the puzzle. Notice that in each row, column, and region, only the numbers 1 through 9 exist.

Some variations of Sudoku use grids of different sizes. For example, some "Mega" Sudoku puzzles can use board sizes of 12 by 12, 16 by 16, and even 25 by 25. There are also "Kids" Sudoku puzzles, which generally have a board size of 4 by 4, or 6 by 6. There are also Sudoku puzzles that use colors, shapes, or letters, instead of numbers.