In this video I'm going to show you how to solve a 4x4 Rubik's Cube
Check out my other videos showing you how to solve a 2x2 Rubik's cube, a 3x3, a 4x4 and even a 5x5
Okay, so now we've matched and orientated all the centers and we've also paired all the edge pieces
We've now basically got a scrambled 3x3 cube
And we're going to start and assemble this cube as though we would a 3x3
And this is why you really need to know how to solve a 3x3
Because I won't go into great detail on how to solve a 3x3 in this video
Please check out my 3x3 video in order to understand what we're doing
Also when using algorithms with a 4x4, I just need to explain a little addition to the formula that we use
We still use F, B, L, R etc for the front, back, left, right faces
And they're capital letters
The capital letters denote the outside faces so.. R
Ri
L, etc.
U
However, we've also got inside layers on a 4x4
And if you want to turn just one of these or if it tells you to turn just one of these
That would be a small letter of the corresponding letter
So small r would be the inside one
Small l would be the inside one
And you notice I'm turning two and then turning it back just because it's easier than trying to turn one
So that is actually a small r
But I just do both and then back
So I have turned just the small r
Now if you see a small r with a large R in brackets, so both of them together, that means move both of them
So (Rr)
Is both
And it's exactly the same for all the other letters
Large U small u in brackets (Uu)
Large U
Small u
And it's the same if you want to turn anti-clockwise, it's the same you just have an i after it
I use i [for inverse], that's just the way I learnt many years ago
Think a lot of formulas actually teach you an apostrophe '
So, small Ri
(Rr)i
And also if we want to turn a piece 180 degrees we don't write RR
RR
Just so we don't get confused with (Rr)
We write R2
So, R2
One, two
Same with r2
That is r2
And (Rr)2
And it's the same for all the others
(Uu)2
U2
And u2
Ok
So on the 3x3 we started on the green face, so I'm going to start on the green on this
Remember this is our center piece
And the first step is, we started making a cross so I'm going to make a cross
Making a cross, also paying attention to the side colours
So now I've made a cross
Stage 2 was matching the corners, putting the corners in place
So now we've got the first face made and we've also got our first row
This would be like the first row on the 3x3 and we would have like a T
Then we would turn it over putting this green face on the bottom, so the green face now is always our D face
And the next step will be to put these pieces into this position
We would need to find where it needs to go, these two colours and these two colours need to match
And then line the side colour up
And you drop the pieces down here like a 3x3
If you need that explaining then go and watch stage three in my 3x3 tutorial
And it's U R Ui Ri Ui Fi U F
U R Ui Ri Ui Fi U F
Final one
U R Ui Ri Ui Fi U F
Okay, so now we've done the first three rows that will be the same just doing the first two rows on a 3x3
And if you remember
The fourth step was making a cross on the top
You either started with just one piece like I have here
Or you started with an L
Or you started with I
Or sometimes you get the cross
Well it's exactly the same as what we do now
So that would be the FRU RUF algorithm
F R U Ri Ui Fi
Then put it to the back
F R U Ri Ui Fi
And now we've got the cross
However..
However, you might find yourself in this position
Where you can't make a cross, you've got a T
Where these two colours are flipped
Or, you might have started off in this position..
Where you only have one
As you know, this is impossible on a 3x3
You can't have just one and you can't have just three
You either get the cross, the L, the line or just the middle
Well, this is a parity [error]
On a 3x3 it would be impossible, on a 4x4 it is possible
So if you get this the first step we need to make it into the T that we just had, so to do that
Imagine that this is your line and then you're going to turn the line into the cross using the FRU RUF algorithm
that I taught in stage 4, so we'll just do that
F R U Ri Ui Fi
If that was a 3x3 we'd now have a cross but we don't, we are in parity because we've now made the T
And we're in parity because these two colours are flipped
As I said
It's impossible to get this scenario on a 3x3
If you do get it on 3x3, I know I've just said it's impossible
Impossible because it means this piece has been removed, turned and put back in
And it would be impossible to solve a 3x3 like this. You would need to take this out, turn it and put it back.
So what do we do? We need an algorithm to sort out this parity
The algorithm will turn this blue up here and this yellow down here
And to do the algorithm you need it in this position so it's on the top front face
And this is the one we working on
Now unfortunately, this algorithm is quite long
So the algorithm is.. get ready!
(Rr)2 B2 U2 (Ll) U2 (Rr)i U2 (Rr) U2 F2 (Rr) F2 (Ll)i B2 (Rr)2
A hell of an algorithm to remember I'm afraid but there's just no avoiding it for a 4x4
So let's do the algorithm, again you want this to the top and to the front
These are the two we want to flip, so this is how they want to be
And then we go..
(Rr)2 B2 U2 (Ll) U2 (Rr)i U2 (Rr) U2 F2 (Rr) F2 (Ll)i B2 (Rr)2
And that has flipped these two pieces getting us back out of parity
So now we're back to the cross where we was a moment ago
So the next step in solving this Rubik's cube
We would normally do these edge pieces. On 3x3 we would now position these edge pieces
However, there is a chance of two more parities
There's a parity on the corners and there is a party with these edge pieces
Now what I do..
The algorithm to solve the parity on the edge pieces is quite simple to remember
When you do the movements you realise just how simple it is
The algorithm on the corner pieces is extremely complicated
But there is a way of avoiding the corners from being able to go into parity in the first place
And that is to set the corners before we do the edge pieces
So we set the corners just how we would normally and pretend that we've already done these [edge pieces]
So find one corner that's in the correct position
And lo and behold it, they're already in the right position, but imagine they weren't..
So imagine the weren't already in the correct position, this one is, this one isn't, this one isn't, this one isn't
And that's what we want, we want three that are not in the correct position
If we'd already done these sides and put them in the correct position
Sometimes you can't, you can only get two out of position
and then your corners are in parity
But by doing the corners first that won't happen [because you can turn the top]
So now let's put the corners in the correct place using the formula we know from the 3x3
U R Ui Li U Ri Ui L
We need to do it one more time
U R Ui Li U Ri Ui L
And now we've got the corners in the correct position
And now we go on to move the edge pieces
Maybe these are in parity, maybe they're not
This one to go here, this one to go here, this one to go here
This time these pieces are not in party
I will show you what happens if they are party in a moment
But for now we'll just complete the cube
So now we put these in position using the..
R U Ri U R U U Ri
And now we've put these in the correct position which is mixed our corners up
However, they are mixed up out of parity
If they was in parity they'd now be in parity
But because we set them correct earlier
It doesn't matter that these are mixed up, they're now mixed up as though they're in a 3x3
And a 3x3, these cannot go in parity
It's a step I recommend you do
Do the corners first and then when you correct these, then mess your corners back up
And now you just set these corners like you would if it was a 3x3
If we find one..
We haven't got any in the correct position so we just do the formula
U R Ui Li U Ri Ui L
Find on that's correct
This one is, and then..
U R Ui Li U Ri Ui L
And there we are
And then just do the normal formula for turning the corners in the correct rotation
If you don't understand this one again, this is step 7 in the 3x3
[Ri Di R D Repeated]
And that would solve the cube
But we didn't get any parities so now I'm just going to alter the cube
and deliberately put them into party
Okay, so now we get into this position, I've deliberately set these edge pieces in parity
We've got the corner pieces in the correct place
I've just rotated them as well so you can easily see they're in the correct place
But these edge pieces are in parity
We've got this one here incorrect, this one here incorrect, this one here correct and this one here correct
And we don't want to turn these because we don't want to mix up our corners
So these are in party. If you remember we need three that are not in the correct positions
And we've got two that are not in the correct positions
What do we do?
Well the algorithm to get out of parity moves these two here for these two here
It swaps these two
You see this one's yellow, so if we move this one to here, this one will be incorrect
This is orange, even though it's correct we'll move it to here
Will be incorrect, so we'll be left with three incorrect
And that is how we solve the parity
If we solve this the normal way by just turning it so we do have one in the correct position
And doing the algorithm now, we would put the parity into the corners, it's an endless loop
So we don't want to turn it, we want to keep the corners in the correct positions
Otherwise, the corners will be in parity
And the algorithm for that is huge
The algorithm for getting the parity out of the edge pieces is quite simple
So once you've set your corners
Then come to set your edge pieces
If you are in parity as we are here
You need to do the following
Just swap two pieces around
Doesn't matter if you've got correct here, correct here, incorrect, incorrect here
You swap them around until you've just got one correct
These are correct, these ones aren't
But if I bring these to here they will be incorrect
And if I move these to here they will also be incorrect
Then we will be left with three incorrect and we can do our normal algorithm
And the algorithm for this is really simple, It's..
r2 U2 r2 (Uu)2 r2 u2
And now we just do the standard algorithm to move these in a counterclockwise direction
R U Ri U R U U Ri
Now we've moved these into the correct position, that has now mixed our corner pieces up again
But they are mixed up as though they are mixed up on a 3x3, in other words, they are not in parity
So now we don't have any in the correct positions
We just do the algorithm to put at least one in the correct position
U R Ui Li U Ri Ui L
And look around
Have one in the correct position here
And this one isn't, this one isn't, this one isn't, and we can do the normal algorithm
U R Ui Li U Ri Ui L
And now the other three are in the correct positions
And we just do the final algorithm on the 3x3 to rotate the corners
[Ri Di R D repeated (3x3 step 7)]
And there we go
Hope it helped and thanks for watching!