Sudoku Rules

This page summarizes the basic sudoku rules before you play our free sudoku puzzles. Other pages that you might find useful include a page covering the history of sudoku and a page with some basic sudoku tips.

Structure of Sudoku

Sudoku, a logic-based number puzzle, is very simple and very fun to play.   While the puzzles can range in difficulty from easy to very difficult, the basic premise remains constant, regardless of the challenge.  The game consists of a square grid with eighty-one boxes arranged in nine rows of nine squares each.  Some of the squares on a puzzle will already contain numbers.  These numbers are sometimes referred to as “givens.”

The Basic Rule

The fundamental goal of a Sudoku puzzle is to use the provided numbers, or givens, to discover which numbers logically fill in the empty squares.  The only rule of Sudoku is that each of the nine rows, each of the nine columns, and each of the nine 3x3 subsections must contain all of the numbers from one to nine, and each number consequently can occur in each row, column, and subsection only once.

Minimal Math

While Sudoku deals with numbers, logic and reasoning skills, rather than arithmetic abilities, bring success.  The sums of the numbers found on each of the rows and columns are irrelevant, and have no bearing on the game.  In fact, since each row, column, and subsection contain nine digits with values from one to nine, the sum of each is exactly the same: 45.  As you complete your Sudoku puzzle, you need not pay attention to adding the numbers.  Instead, just focus on making sure each row, column, and subsection contain just one instance of each number between one and nine.