This article will outline the Petrus method of solving the Rubik's Cube.
In this article, I will outline what is, in my opinion, the best method of solving the Rubik's Cube. This method was developed and used by Lars Petrus, and was the way I first learned to solve the cube. There are many other popular ways to solve the cube, but this method is proven to be the fastest and easiest way to solve the cube.
In many other methods, the cube is solved one layer at a time. This is very inefficient in terms of moves, because you have to break your finished layer(s) many times to solve the rest of the cube. This method works a bit differently, first by completing a 2x2x2 block on the cube, and continuing to build from this. Using this method, you can make more efficient use of your moves, thus reducing the total number of moves you need to solve the cube and, in turn, reducing the time it takes you to solve the cube.
This method is perfect for beginners and speed-cuber's alike. Enjoy!
The cube as it appears unsolved.
Step 1 - Solve a 2x2x2 corner
To complete step one, pick a corner, let's say the red-blue-white corner for the sake of this tutorial. Then, your next task is to align the red, blue, and white center pieces with the respective sides of the corner you chose. When this is done, align the red-white middle edge, the red-blue middle edge, and the white-blue middle edge into their correct places. If done correctly, you will now have a 2x2x2 corner of the cube solved!
The 2x2x2 corner solved!
Step 2 - Build your corner to 2x2x3
Completing this step is easy; expand your 2x2x2 corner to include another two edges and the corner in between them. All of the center pieces are already in the correct places, due to your original alignment, and thus, when you have inserted the 3 aforementioned pieces into their correct spots, you will have a 2x2x3 cube solved.
The 2x2x3 block solved from angle A.
The 2x2x3 block solved from angle B.
Step 3 - Ensure the remaining middle edges are correct (make crosses)
To complete this step, you must take the remaining two sides and ensure all of the middle edge pieces are correctly oriented with their respective center piece. The corners do not have to be flipped correctly at this point, but if you do this step correctly, the middle edge pieces should form two crosses with their respective center pieces.
As you can see, the green and orange edges are correctly oriented, forming the two "crosses".
Step 4 - Finish the 2x2x3 to make a 2x3x3 (bottom 2 layers complete!)
At this step it is inevitable - you must complete the bottom 2 layers to continue. To do this, begin by completing a corner and its two adjacent edges. When this is complete, move the remaining edge and corner into place at this same time, thus completing the bottom 2 layers of the cube.
The bottom two layers solved from angle A.
The bottom two layers solved from angle B.
Step 5 - Ensure the corners are oriented correctly
In this step, you must ensure the corners on the top, unsolved layer are oriented correctly. To do this, match one corner up in its correct spot, and look to see if the other corners are also correctly matched up. If they are, great! Move on to step 6. If they are not, you must attempt to exchange the corners until they are correct. To do this, you must break the bottom two layers, but there are certain algorithms that you can find that will allow you to swap the corners without ruining your progress. See the end of the article for a link to such a solution.
As you can see, the red-white-green corner is positioned correctly. If the others are as well, move on. If not, swap them until they are!
Step 6 - Ensure the corners are positioned correctly
This step involves flipping the corners, such that they are in the correct position to solve the cube. Again, you must break your progress to do this, but there are algorithms that will allow you do break your progress and restore it, while also flipping the corners into their correct positions. When you have completed this step, the entire top layer will be facing in the correct direction, and only the middle edges will have to be exchanged for you to complete the cube!
The top layer oriented correctly from angle A. Almost there!
The top layer oriented correctly from angle B.
Step 7 - Swap the edges
This is the seventh and final step in the Petrus method. To complete this step, simply follow an algorithm that will allow you to exchange the middle edges of the cube without ruining your progress thus far. When complete, sit back and pat yourself on the back! Not many people who pick up the cube can solve it, and you are sure to impress many people with your quick and efficient solution.
Done! From angle A.
...and again from angle B!
I hope you have enjoyed reading this! The algorithms I mentioned can be found on the Petrus creator's website, which can easily be found through a quick google search.
This method will be faster and more efficient than any other method you will find on the internet. Do not waste your time with other methods! This is the best and will allow you to quick and easily solve the cube, and beat your friends when having a speed-cubing race!
Until next time...