The selection of a Difficulty level indicates how hard it will be to solve the Sudoku puzzle.
The more difficult the level, the harder it will be to figure out which numbers go into the empty
blocks. Note: More difficult levels do not necessarily mean less blocks will be pre-filled in
the initial puzzle.

Puzzle ID

Often you may want to share a specific puzzle or print a puzzle solution some time
after the original puzzle was created. This can be done by using a puzzle ID. A puzzle ID is a six (6)
character identifier that represents a specific Sudoku puzzle that was previously
created. You can obtain a unique puzzle ID by viewing your original puzzle; it is
located in the bottom-left corner of the puzzle (e.g. MWYJKK). When you input a puzzle ID, select
the Puzzle or Solution option, then click the Generate! button to create the solution puzzle.
Note: When a puzzle ID is used, the Difficulty level is ignored as your puzzle ID already
includes this information.

Generate!

The Generate! button allows you to create your Sudoku puzzle. Once you have selected your
Difficulty level or Puzzle ID, you may select one of the following choices below and then click
the Generate! button.

Puzzle - This choice will create a Sudoku puzzle. You can then print the puzzle to
complete it immediately, save it for a later activity, or print it to share with someone else.

Solution - This choice will create the solution to the Sudoku puzzle. The puzzle's original empty
blocks will be highlighted and filled in. You can print the solution puzzle or view it
online to determine if your own solution is correct.

Re-Shuffle

Each time you click the Generate! button you will get the same Sudoku puzzle. If you would like to create
other unique puzzles, then you can click the
Re-Shuffle button. Once you click Re-Shuffle, you click the Generate! button once more to generate
another unique puzzle. There is no limit to the number of times you can re-shuffle to create
additional unique puzzles.

How to play Sudoku

A standard Sudoku puzzle consists of a grid of 9 blocks. Each block contains 9 boxes arranged in 3 rows and 3 columns.

When you start a game of Sudoku, some blocks will be pre-filled for you. You cannot change or move these numbers in the course of the game.

Each column must contain all of the numbers 1 through 9 and no two numbers in the same column of a Sudoku puzzle can be the same.

Each row must contain all of the numbers 1 through 9 and no two numbers in the same row of a Sudoku puzzle can be the same.

Each block must contain all of the numbers 1 through 9 and no two numbers in a single block of a Sudoku puzzle can be the same.

There is only one valid solution to each Sudoku puzzle. The only way the puzzle can be considered solved correctly is when all 81 boxes contain numbers and the other Sudoku rules have been followed.

You can view a detailed explanation on how to play Sudoku on Wikipedia.

When a puzzle is complete, the solved Sudoku puzzle appears as shown (white blocks are the ones filled in to solve the puzzle):