Before this year wraps up, it should be noted that this year saw the 25th anniversary of the Rubik's Cube's original release, so I figured it was time to revisit this classic puzzle.

Rubik's cubes, of course, are mainly for solving, and one of the most popular ways to do this is to solve for speed. But how do you go about solving it in the first place? If you're new to the cube, solving methods and notations, a great place to start is Jasmine's Beginner Solution to the Rubik's Cube page. She builds up a basic method, and then goes on to describe more advanced strategies, once you're comfortable with her basic method.

Another good beginner's page with graphic notation of what each move actually looks like is Joel's simple solution. This, and many of the other following pages that teach Rubik's Cube solutions, use Java to simulate the cube, so you'll probably want to make sure that you have the latest version (free download).

If you want to start getting into it for speed, check out Solving Rubik's Cube for Speed.

One of the more interesting speed methods is Philip Marshall's ULTIMATE SOLUTION TO RUBIK'S CUBE. With this method, there are only two different series of moves you have to learn to solve it in an average of 65 moves!

Solving the cube, even for speed is only one way to approach it. Here's a Perpetual Calendar Rubik's Cube, in which you simply have to solve one face for the current date. Unfortunately, you can't buy a real version of this anywhere. However, you can make one with the aid of a blank cube, some customizable Rubik's Cube stickers, and the proper layout of the stickers. The customizable stickers also come with a Word file for a different perpetual calendar, which is also designed to display the year!

Another unique challenge is to learn to solve the cube blindfolded. One of the most comprehensive methods of doing this is to learn the method at Jessica Fridrich's Speed Cubing Page without a blindfold, and then learn Richard Carr's adaption of this method for blindfolded cubing. Richard Carr's additions are written in simple text with no paragraphs, so it should be copied to your favorite text editor or word processor to make it more readable.

Of course, another alternative is to learn any of the methods above, and use a different kind of blindfold.

Thinking about the calendar cube and the blindfolded cubes gave me an idea for a bizarre, untried idea. Imagine you're given a scrambled perpetual calendar cube to examine for a minute or two, and then you put on a blindfold. At that point, someone gives you a date, such as "July 26, 1980". Not only do you solve the face of the perpetual calendar to show July 26 (or July 26, 1980, depending on the version you're using), but the cube also shows the correct day of the week (Saturday, in our example)!

This is a mix of any of the above blindfolded methods, combined with the classic Day For Any Date feat. I'd think the toughest part of this routine would be presenting it without looking like a show-off.

Don't think I've forgotten about those who prefer to admire the cube in a hands-off fashion. Take a look at the breathtaking Three-dimensional designs of Dr. Hana M. Bizek. He's a Rubik's Cube solver who likes to arrange large groups of cubes together in order to form artistic patterns. Among my favorites here are the Jaroslav and the Landry staircase.

If this still isn't enough Rubik's Cube information for you, then I can only hope that Jaap's Puzzle Page, especially their Rubik's Cube, Rubik's Revenge and Mini Cube pages, offer enough links to sate your curiosity.

What?!? You haven't finished your Christmas shopping for your favorite geek yet? In that case, I have some updates to the 2005 Grey Matters Gift Guide:

Starting with my personal favorite, Pi-related items, ThinkGeek has reponded to those of you who think it's too cold for Pi T-shirts and Pi babydolls, by bringing us the Pi hoodie!

Of course, staying inside can also help keep you warm. However, to really get that blood circulating in the brain, I suggest playing Polarity. Imagine magnets meet Reversi (also known as Othello), and you'll start to get the idea.

Here's a great post from John Biesnecker, an American who is currently living in China. He shares his experiences and often amusing personal mnemonics as he learns to read and write Chinese characters.

This post is a good example of why, as useful and as powerful as mnemonics can be, it's often best if you keep them private.

Even if you've never thought about competing in the World Memory Championships, about which I've written before, you may still wonder what it would be like, and how you would stack up. If so, I have great news for you!

Tony Buzan, founder of the World Memory Championships and the Buzan Centres, has created an ongoing online memory contest that anyone can enter as much as they wish. This contest is called the World Memory Challenge!

The challenge consists of at least 3 tests, more if the website determines you can handle further tests. The tests consist of things like memorizing the order of playing cards and other symbols, matching pairs of cards, and even matching names with faces. To get an idea of how the various challenges are presented, check out the online tutorial first.

A score is kept as you play, but you don't see it until you go as far as you can with the tests. The site lets you see your full ranking details if you enter your e-mail address. To compare your scores in various ways, the site also keeps track of constantly updated statistics, so you can see how you measure up against the average in your own country, against other countries, by gender, age and even occupation!

If, like me, you would be interested in seeing how well the average reader of Grey Matters does, please post your best scores in the comments! I'll keep my best score updated in my profile, for those who are interested.

Oh, and if you need any help improving on the tests, then simply spend more time reading this blog!

So, you have a friend or family member who's a math and/or memory geek, but you're not sure what to get them for the holidays? Not to worry, the 2005 Grey Matters Gift Guide is here!

What better place to start than a T-shirt featuring a mnemonic on it? This T-shirt from ThinkGeek.com features the classic mnemonic for the formula for sulfuric acid:

Johnny was a chemist's son,
But Johnny is no more.
What Johnny thought was H₂O,
was H₂SO₄!

Of course, where math and memory skills meet, Pi is always there! For those who enjoy the classic challenge of Pi, you can encourage their achievements with a T-shirt featuring 4,493 digits of Pi! Don't forget, though, that there are ladies out there who take on the challenge. For them, there's the same t-shirt design available in babydoll style.

I can here some of you saying, "Sure, T-shirts are a great Christmas gift in some places, but what about those of us in the northern hemisphere?" No problem! Just wrap yourself in a nice, warm blanket, featuring the first 410 digits of Pi. I'll even help you memorize 400 digits of Pi at no extra charge. You're on your own for the remaining digits, however.

Before we leave the Pi-related gifts, why not tell the world how easy memorizing Pi can be, with an "Simple As 3.141592..." T-shirt?

That last T-shirt is put out by the good people at mental floss magazine (yes, I meant to type the magazine name entirely in lower case). Mental floss's motto is "::Feel Smart Again::". Although it is one of the more inexpensive gifts in this guide, a mental floss subscription can help your favorite geek or trivia lover feel smart all year (assuming you're not trying to avoid that)!

Speaking of reading material, there is a great selection of Memory & Mnemonics ebooks from Lybrary.com, including the hard-to-find "How To Develop A Perfect Memory", about which I wrote in my second blog post.

If your favorite geek leans more towards math, then the Martin Gardner's Mathematical Games CD-ROM, containing all 30 years of the mathematical master's Scientific American columns should be just the thing.

For someone who likes to perform the calendar recall feat, but never seems to have a portable perpetual calendar around for verification, perhaps a Calendar Wheel, or a nice wooden perpetal calendar from Sculptures-Jeux would come in handy.

But for something really special, let's consider the Knight's Tour. The mathematicians can do the Knight's Tour their way, and the memorizers can do the Knight's Tour in a completely different way, but they both still need a way to demonstrate the feat. To answer that want (need?), we have the Knight's Tour Excalibur by Devin Knight, complete with 3 different size chessboards for different audience sizes, as well as plenty of extras. For those who would like to be able to do the Knight's Tour, but don't want to put in the work, it even includes a method that makes performing the Knight's Tour much simpler, yet doesn't interfere if you wish to perform the legitimate versions!

I'm just doing my part to make your holidays happier and geekier.