Solving a Rubik’s Cube.

The Rubik’s cube is one of the most difficult mainstream puzzles ever created. Most of us have probably seen it and had a go at trying to solve it, but a lot of us, including me, have never actually solved it...

I came across a WIRED video by Robbie Gonzalez that was titled ‘How to solve a Rubik’s cube’. “Hmm… This doesn’t look so hard. I bet I could do that.” Curiosity got the better of me and I found myself on Amazon a few moments later impulse buying a cube for myself.

A few videos later, I learned that the Rubik's cube has over 43 quintillion possible combinations - That's more combinations than there are grains of sand on all the beaches in the world! Oh dear... What hope do I have? But I also learned that no matter how jumbled a Rubik's cube is, it is always no more than 20 moves away from being solved. What!? Okay... I don't know what to feel now.

The cube arrived the next day and I immediately opened it up and spent my time on nothing else until I went to sleep that night. The video had a few easy steps to it but it quickly developed into some daunting algorithms that I hadn’t really thought about until I looked down at the unsolved cube in my hands. Watching the video along, pausing at points, rewinding parts, I solved the cube the first time in around 20 minutes.

The second time, I wanted to solve the cube without the video. This took a lot longer: I wrote down only the algorithms I was likely to forget, giving myself as few clues as possible to test my memory.

Okay, what is an algorithm? Essentially it is a series of moves written out in a certain notation, that tells you how to achieve a certain change to the cube. Don’t be scared off, it’s easier than I make it sound: Each face of the cube has a letter assigned to it: the right face is R, the left face is L, the upward face is U and the forward face is F. (There are also letters for the back and downward face, B and D, but for some reason, I didn’t have to use these letters.) In the algorithm, a letter is written (e.g. R) to tell us to rotate this face clockwise. To tell us to rotate that face anticlockwise, it is written R' (read as ‘R prime’). That’s all there is to it.

This attempt made me realise that I really had no idea what I was doing, BUT it gave me very useful information: It told me specifically where the gaps in my knowledge were. After this I cycled through a little process: I would see how far I could get on my own, tick off the steps I had mastered and then focus on the rest of the steps. The third, fourth, fifth attempt, etc. I would get stuck or mess up somewhere along and I’d have to check the video for the one piece of information I needed.

The algorithms (as pictured from my crude notes):

At some point, with the use of my notes, solves would take around 5 minutes each. However, to be able to solve a Rubik’s cube myself, I had to get rid of my notes entirely and commit to memory a few, rather long algorithms. At this point, it started to feel a little less like a toy and a little more like revising for a test, but this difficulty made it so much more rewarding when I was able to achieve results.

These notes probably won't make much sense to you, and I won't bore you with the details, but I want you to appreciate how daunting a task this was. Each algorithm has its own unique purpose, may need to be performed multiple times, and has particular prerequisites to being used.

"Okay, this is just a memory thing. Should be simple." I had to dust off my knowledge of memory techniques and remind myself how to revise.

The video gave me my first technique: The Mnemonic. The algorithm for solving a yellow cross goes like this: F U R U' R' F'. Simply pronounce the word it makes: "fur-urf" and that's a lot easier to commit to memory. All I had to remember was that the second half of the word are all primes.

For the other algorithms, I used a memory technique called chunking: I split the algorithm up into workable pieces and pronounced those out loud. The tricky part was remembering which letters are primes.

I also used imagery as memory triggers, for example, the chunk: U R U2 - I thought about being at a U2 concert and pointing to the stage yelling "You are U2!" It's silly, I know, but it's memorable and that's the point.

Performing one of the algorithms (F2 U R' L F2 L' R U F2), was a strange experience: Before I could come up with some way to remember the algorithm, the ‘hands-on’ part of my brain realised it was palindromic - It felt like a mirrored sequence of moves. For some reason, reading it out loud I didn’t realise that. I feel as if that algorithm slotted into my brain in a different way.

Having spent a few hours on the cube that night, (receiving a few concerned comments from parents), I went to sleep with cube faces passing by on the inside of my eyelids.

Spending an hour the next morning, I was able to solve the cube by myself, for the first time. It was incredibly shaky and I couldn't quite believe myself. It felt like I was a baby deer, who was just learning to walk - I don't quite know what I'm doing but somehow I'm doing it!

At this point, solves would take around 5 to 10 minutes each. I did it over and over again, I would discover new edge cases, get stuck in loops, but I learned how to solve those issues. Another hour later, I was able to solve the cube consistently in under 5 mins each time. I called it there - I can now solve a Rubik's cube.

My fears of those long algorithms had subsided - Once you know it, it doesn't seem so hard. It's like most things: riding a bike, driving a car and (I can only presume) piloting a plane. It just takes some effort, and sometimes, it’s really fun.