Archive for May, 2005

Sudoku Addict

Are you a Sudoku addict? Check out this article by Seth Stevenson… My Days Are Numbered – I’m addicted to a Japanese logic puzzle. You will be, too.


Zen and the Art of Sudoku

I gotta tell you, some people get very involved with these Sudoku puzzles!

And I don’t just mean figuring out how to solve them. I mean looking at the deeper meaning, the philosophical questions that surround our much-loved 9 x 9 grid.

Check out OddThinking – Get a Sudo-Clue! for a discussion on whether or not solving a Sudoku requires mathematics…


Sudoku: Information From

Thought you might like to see what the good people at have to say about Sudoku. Sourcing their information from Wikipedia, they give a great overview of history, methods, computer solutions, construction, variants and the mathematics behind the puzzle. have a look and see what you think.

– Tim.


Sudoku Dashboard Widget

All of you Mac users are in luck – you can now have Sudoku directly on your dashboard. Check out Apple – Mac OS X Downloads – Dashboard Widgets – Sudoku Fun. And for the rest of us PC users we are just jealous… 😉


Eat eggs and play Sudoku if you want to be brainier

We all secretly knew this to be true. But now the next time someone tells you to “Stop wasting your time with those silly puzzles and do something constructive”, you can say “Hah! This is making me smarter!” Here’s proof!


The Mail online’s Sudoku challenge

Just can’t get enough Sudoku? The Daily Mail has links to a week’s worth of Sudoku puzzles in varying degress of difficulty, in their Mail online’s Sudoku challenge.



Sudoku puzzles: kids

Sudoku puzzles: kids


Another Sudoku Solver program

Here is another useful little Sudoku Solver freeware application. I haven’t found a Sudoku yet that it can’t figure out! (please post a comment here if you find one that stumps it)

I think it was a bit of a lunchtime distrction for the guys down at DeadMan’s Handle (data protection for laptops).

It features:

  • Integrated help.
  • Saving and loading of puzzles and solutions.
  • Scan of input data for obvious errors.
  • Very fast solution times.
  • Identification of malformed puzzles.
  • A training mode.
  • Maintenance of an eMail template.
  • Quick sending of a standard solution eMail from the template.
  • Generation of text messages for use with non-SMTP mail systems.

Of course, you could use the email feature for emailing in your answers quickly to the newspapers that run competitions, but we wouldn’t do that because that would be cheating, wouldn’t it?!!??…



Sudoku On Your Pocket PC

Wow! I have just installed Bunnyhug’s Sudoku for Pocket PC. I’m impressed!

So kewl … now I can play Sudoku on the train without needing to remember to bring a pencil & eraser!

They offer a trial version, which is limited to only allowing you to play about 30 fairly easy puzzles. Then you can splash out with a huge US$3 ( agast!) to download the full version, which has 300 built in puzzles, plus a puzzle editor for creating your own puzzles (or entering puzzles from the paper or magazines), plus a random puzzle generator.

You can enter up to four ‘scratch pad’ numbers for each square. The interface is very easy to use, and after a bit of familiarization you’ll be hooked!

Click here to have a look.


Solving SuDoku Puzzles

They say that one of the best ways to learn something is to watch “over the shoulder” of an expert and learn from what they are doing. Roger Walker is such an expert, and he has kindly made a couple of walkthroughs with details of his logic and reasoning at each step of the way.

Very helpful! Thanks Roger!


Sudoku helper/solver

The good folk at MPP have put together a nifty little Sudoku Helper / Solver. It is freeware, although they take PayPal donations if you want to support what they are doing.

It has a useful feature to easily display which numbers can be entered into each square, although the interface is a little clunky (you can’t just type in a number, you have to right click and select the number to enter it).

It has a built in ‘hint’ facility (eg “The cell at row 4, column 5 is the only possible location for 4 within its group.”), or you can just get it to solve the puzzle outright (is that cheating?…. :-). Although I did find with really tough puzzles it sometimes cannot figure them out. I guess there’s no substitute for the grey matter after all…

Another great feature is the ability to create puzzles, with 5 levels of difficulty rated from Trivial through to Hardest. In fact the hard puzzles are so hard that it is not always able to solve its own puzzles!

All in all, it is a great little utility with some useful features. And you can’t really go wrong for the price!

Have fun,


Sudoku Solutions

If you just can’t wait for the solutions to the Sudokos published in England’s newspapers, click across to SudokuSolutions and find the answers even before the papers print them!

This site is brand new – and currently only has the answers to the Guardian’s 27th may 2005 edition. But stay tuned – this looks like it could be the start of something big…


You can’t please all of the people …

We have all experienced the frustration of staring at those squares with no idea of what to do next. I guess it just all gets a little too hard for some people. Ah well, you can please some of the people some of the time, but you can’t please all of the people …


3D Sudoku!

Now it’s just getting silly! 🙂

The Daily Telegraph has published an article on the Dion Cube™ – think of a cube made up of nine layers of Sudoku puzzles.

Not only must each number only appear once for each 3 x 3 square, each row and each column, it must also appear only once for each ‘vertical column’ – ie. each corresponding cell in all of the layers above and below it.

As they say, a picture is worth a thousand words, so enough with the talking and on with the puzzling! (note, you will need Adobe Reader for this one… Use the “Get Adobe Reader” link over on the right if you need the free reader software).

Have fun,



Is Guessing necessary?

Here are a few thoughts on whether you can always solve a Sudoku by logic – ie. without having to resort to guessing.

The answer is that for most simple puzzles simple (or fairly complex) logic will solve the puzzle, but for more difficult puzzles you will need to guess for at least one square – after which you should be able to fall back on good ol’ logic to finish the puzzle.

The Sudoku Programmers forum gives you a few different methods for guessing (gee, and I thought it was just ‘think of a number…’). Like X-Wings, Nishio, Swordfish and Jacko!


I feel a little embarrassed! I (almost) completely misunderstood what I was reading when I researched the topics above!

Yes, Nishio is the word for when you make a guess in Sudoku, then back-track if you need to if you hit a dead-end.

But X-Wings, Swordfish and Jacko are different patterns of numbers that appear in the puzzles, each one with a specific way of solving them. Stay tuned for a future post when I have got my head around them enough to introduce them properly!

Have Fun!


Britons trapped among 81 squares

The Star-Ledger from the USA gives us their spin on the Sudoku craze that is sweeping Britain.

I like the way that the word ‘Sudoku’ is creeping its way into our common language:

“A Times columnist wrote dismissively about Prime Minister Tony Blair’s recent Cabinet shuffle: “It is not exactly Sudoku, is it?” “


Guardian Unlimited – Insanity by numbers

Justin McCurry takes up his chewed pencil stub to report from the home of Sudoku on how the little grids became such big business, in Insanity by numbers.


Sudoku Speed Challenge

Click through to Sudoku Fun – A new puzzle everyday to enter their Speed Challenge.

Fill in the onscreen grid in the fastest time, and get your name up on the leader board!



Just how many Sudoku combinations are there?

For most of us, we can just glaze over here, but I thought I’d add this fun little sequence for the mathematicians amongst us.

The question is: If you start from a blank Sudoku grid, just how many different combinations can you have?

There is (wait for it…) 11 pages of forum thread on

Thankfully a very wise person called Bertram has posted a solution.

The final calculation is:
2^15 * 3^8 * 5*7 * 27,704,267,971 = 9! * 72^2 * 2^7 * 27,704,267,971

And the final answer is (drum roll please…)

But…. does anyone know how you say it (are we talking about trillions, gazillions, scadillions…)?


Daily Mail claims Su Doku

The newspaper war hots up in England. Read a nicely balanced summary of the claims and counter-claims here: – Daily Mail claims Su Doku.

I agree with the final quote:

“I propose a truce. We’ve all got one now, let’s just leave it alone. Do the puzzle, don’t do the puzzle, just don’t talk about it.”


The Times brings cult Sudoku craze to mobile phones

Revolution Web Site: “The Times brings cult Sudoku craze to mobile phones”

Now you can take your Sudoku with you wherever you go! Well, at least if you live in the UK. Hopefully some newspaper publishers catch on in other parts of the world soon…

Here is the link to the Times Online web page where you can sign up if you live in the UK and meet their other requirements.


Daily Sudoku Game

Mousebreaker Free Online Games – Daily Sudoku! Game

Here’s a site worth checking out. They have a really spiffy interactive game interface, that even lets you put in a few options into each square while you are working it out. And then, for your five seconds of fame, you can enter your name into the hall of fame when you finish!

Definitely worth bookmarking.




The Daily SuDoku

Here’s another great site for those of us who just can’t get enough Sudoku.

The Daily SuDoku

They’ve even got a downloadable puzzle book with some ‘back issues’! Stop already!! My brain’s heading into melt-down!



Blank Sudoku Grids

You’ve been there, I’ve been there; you are two thirds of the way through a puzzle, with little numbers written in, crossed out, written in again cause you made a mistake, and it’s all just one big mess!

Here’s where the blank grids come to the rescue. Already ruled up for your convenience, all you have to do is print them out, fill in the starting numbers and you are off and running.

Click here to open them in a new window.


Super Sudoku

Just in case a 3 x 3 grid (81 squares) is not enough for you, The Independent has released a version in its weekend edition of a 4 x 4 grid (256 squares), called the Super Sudoku. Because we run out of numbers at 9, it uses the computer number base hexadecimal, which uses the letters a – f to signify 10 – 15.

I guess they figure that you have the whole weekend to get it done! Then you have to go back to work on Monday to let your brain recover!


Free Sudoku Workpad

The nice folk at have made available a free Microsoft Excel based tool to help with solving Sudoku’s.

It can be upgraded for a few dollars to enable a bunch of features, including making it into an automated solution aid, and to link in automatically with The Times in England, making it easy to send in your answers for their Sudoku competitions.

Note: Unfortunately it requires the use of macros, and so you may have to turn down your level of Windows security in order to use it.


Sudoku Tutorial

Check out this series of tutorials from Let’s Play, a puzzle website in Japan. They take you through the basics, and start to get into some more advanced techniques using animated examples.

Well worth a check if you are just getting started.


Sudoku History

Did you know that Sudoku was originally called Latin Squares? It was invented by a mathematician called Leonhard Euler in the 18th-century. As his eyesight started to fail, he developed the ability to perform complex equations in his head, as well as a talent for designing puzzles.

Then in the 1970’s it reappeared as the Number Place Game in America. In the 1980’s it was picked up by a Japanese puzzle publisher and called Sudoku (pronounced sue-doe-koo). The name is Japanese; su – “number” – and doku – “single”; in kanji it is written 数独. The monthly Sudoku puzzle magazines in Japan currently have a circulation of around 660,000.

In the late 1990’s Wayne Gould, a retired judge from New Zealand visited a bookstore in Japan and a Sudoku puzzle book caught his eye. After several years of research he created a computer program to generate the puzzles, and introduced it to the Times newspaper in England. This seemed to trigger a craze in England, with the newspapers having something of publishing war to try and prove their dominance in the Sudoku market.

More recently it is starting to take off in other places around the world.


A couple of puzzles

Warm up your printer and sharpen your pencil. Here are a couple of puzzles to get you started. I have included a really easy one (if this is your first time), and a reasonably difficult one for if you consider yourself to be pretty good at them!

Click here to open the puzzles in a new window.

Do you want to receive two new puzzles every day delivered directly to your email inbox? Subscribe to The Sudoku Daily Challenge in the box at the top of the page for your daily brain workout!


How To Solve Sudoku

What is Sudoku? How do you play it? What are the tricks and techniques to help you get beyond staring at a bunch of blank squares, and start to fill in those numbers?

Michael Mepham has put together a great guide called, appropriately enough, Solving Sudoku. (If the link does not work, it is likely that you need to upgrade your version of Adobe Reader (free software). Go to and click on the Get Adobe Reader link.) It explains the rules, guides you through the basics, and gives you a quick teaser into the world of ‘Truly Diabolical Sudokus’. You even get four different Sudoku’s to attempt, ranging from Gentle and Moderate, through to Tough and Diabolical! (and it also gives you the answers on the next page).

Click Here to open the guide in a new window.