Know your way around the block

Much of sudoku's appeal stems from its simple setup and instructions.

Each puzzle consists of a grid (see below) divided into 81 squares, arranged as nine horizontal rows and nine vertical columns. The grid can also be divided into nine boxes, arranged three by three, like a tic-tac-toe board, each containing nine squares. A section is a horizontal or vertical cluster of three boxes.

An unsolved puzzle has a sprinkling of numbers from 1 to 9 preprinted within some of the squares. These are the clues (or givens). As a very general rule of thumb, the more clues on the grid, the easier the puzzle is to solve.

How to play: Fill in the squares so that every row, column, and box contains all of the numbers 1 to 9 only once.

And that is the deceptively simple rule of sudoku. Finding the solution requires only logic. No math is involved. And you should never guess (ideally) to fill in a square.




See also:

• Solving Strategies
• Sources for Puzzles
• Stumped and Stumpers
  

• The History of Sudoku