Sudoku Logic
Sudoku Logic
Sudoku is played on a grid of square cells with nine subgrids called blocks. The object of the game is to fill in all the cells with the numbers 1 to 9 such that no row, column, or block contains the same number twice. A particular puzzle starts with some cells filled with numbers that are called the clues.
9×9
3×3
This Demonstration lets you solve several given puzzles or create a new puzzle. The Demonstration does not make any deductions on its own; it is designed to assist in the reasoning process by illustrating various logical steps and solution techniques.
To solve a puzzle, you first analyze the clues (shown in blue) to determine the possibles (shown as small green numbers or squares), which are the potential candidates for a given cell (snapshot 5).
You then apply various techniques to make a choice (shown in red), which may be tentative. You can change a choice if it turns out to be wrong.
You can use various controls to create links (colored arcs) that connect possibles to indicate alternative choices and their logical consequences. See [1, Section 12] for details.
To make a reasoned choice, you must use various techniques (described in the References) to determine which possibles should become choices.
For instance, in snapshot 1, column three has the seven clues 2, 4, 5, 6, 7, 8, and 9 leaving 1 and 3 as possibles in i3 and b3. If the choice for i3 is 3, then h2 must be 9.