Understanding what a house is in a Sudoku puzzle is a key element to understanding puzzle solving techniques. A “house” in Sudoku is a group of nine numbers of 1-9 where each number only occurs once. A house can be a row, column, or 3 x 3 block. There are 27 houses in a Sudoku […]

A Sudoku puzzle is composed of a 9 x 9 grid. The numbers already filled out in are called “givens”. Each number location is called a “cell”. In a 9 by 9 grid there are 81 cells. In this example the givens are colored in black. In this puzzle there are 27 givens filled out.

Every cell in a Sudoku puzzle is shared by three houses (one row, one column, and one 3 x 3 block).  This is an extremely important concept to get about Sudoku puzzles.  As an example, we are going to concentrate on cell R3C5 (row 3, column 5) outlined in black below: The three houses shared