Edges of the yellow cross

A cross, but a crooked one

There's a yellow cross on top, just as we left it last chapter. Now look at the cross edges from the side. Besides the yellow, each one has a second sticker, and that sticker should match the center of its face — exactly like the white cross down below. Here only the front edge matches.

Why not drop the edge down and bring it back up, the way we did with the white cross? Because the first two layers are already solved underneath, and a half turn of a side face would wreck them. We need a move that rearranges the edges on top and, at the end, puts the bottom back exactly as it was.

Don't worry about the corners yet. They're jumbled and twisted every which way, and that's fine. They get the next two chapters all to themselves.

First, turn the top

Start by turning the top layer, and after every quarter turn, count: how many side stickers match their centers? Stop where at least two edges match. There's always such a position. You could prove it, but it's quicker to take it on trust and check.

Here a single U does it: the back edge and the right edge match. Two matching edges are either neighbors, as here, or opposite each other — and each case has its own recipe.

And if all four match at once — congratulations, this step is already done, so skip ahead to the corners. You'll never see exactly three matching: if three edges are home, the fourth has nowhere else to go.

Two neighbors: park them at the back and right

Turn the whole cube so the matching pair sits at the back and on the right. Then:

R U R' U R U2 R' U

This swaps the front and left edges and leaves the back and right ones where they are. The first two layers come through intact.

The corners get shuffled along the way — watch them wander around the top layer. Ignore them: they're next in line.

Why front and left? The algorithm is all right hand, and every turn of the top carries the edges around in a circle. Over the whole algorithm, the back and right edges travel all the way round and come home, while the front and left ones end up swapped. So whatever already matches, you park where it will ride out the algorithm unharmed.

Meet Sune

Inside the algorithm are seven moves, R U R' U R U2 R', plus a final U. Those seven moves have a name of their own: Sune. It's one of the most famous algorithms in all of cubing — just about anyone who has ever solved for speed knows it.

It's easy to remember by its rhythm. R U R' is a short dip of the right hand, U is a pause, and R U2 R' is a longer dip. The last U in our algorithm simply finishes the job, turning the top so the edges line up under their centers.

You'll meet Sune again in the CFOP chapter, where speedcubers use it to twist corners yellow side up.

Sune in your fingers

Cubers love Sune for another reason too: it's comfortable. You play it entirely with your right hand, with almost no regrips. R and R' are turns of the wrist. U is a flick of the index finger along the front edge of the top face, from right to left. U2 is two flicks in a row: index finger, then middle finger right behind it.

Try it on your own cube, slowly and evenly, like practicing scales. If your fingers get tangled, break the algorithm into three chunks — R U R', U, R U2 R' — and drill each one on its own. At first you think about every move. Ten repetitions later your fingers know the way by themselves, and the whole thing takes a couple of seconds.

Two opposites

Here the right and left edges match — they're opposite each other, so there's no way to hold them "at the back and on the right." The fix is simple: play the algorithm once, from any angle. It swaps two edges, which breaks up the opposite pair, and a neighboring pair appears in its place.

Then turn the top again. On our cube, one U makes the back and left edges match — a neighboring pair now. Rotate the whole cube with y to bring it to the back and right, and play the algorithm one more time.

Where people trip up

• Parking the pair in the wrong place. The matching edges go at the back and right. The front and left ones are the ones that get swapped.
• Checking the wrong sticker. The yellow on top looks the same on every edge. It's the side sticker you need to read.
• Turning the whole cube instead of the top while hunting for matches. You hunt with U: the centers stay put and the edges ride around. But once you've found your pair, it's the whole cube you turn to bring it to the back and right.
• Panicking about the corners. They're supposed to be scrambled.
• Dropping the final U. Without it the top is a quarter turn off, and it looks as if nothing matches. If that happens, just give the top that last quarter turn.

Try it yourself

Get all four edges of the yellow cross under their centers. First find the turn of the top where two edges match — you know the rest.

Next: the corners

The edges are home, and the cube looks almost solved. Almost: the corners on top are mixed up and twisted every which way.

We'll deal with them in two passes. First we'll put each corner in its place, without caring which way its yellow faces. Then, in the last chapter, we'll twist them — and see the most beautiful trick in the whole course.