How to solve a Rubik's cube 4х4 - Step 7

Step 7.

In the end of this stage you should have 2 solved lower layers and upper cross.

In the beginning of this step, pieces of the upper cross should be in their place. At the same time, their colors can be upturned. You can have one of the following pictures. All pieces of the upper cross are turned wrongly or

a) 2 adjacent pairs are turned wrongly
b) 2 opposite pairs are turned wrongly

In this step everything is analogous to step 5 for the cube 3x3 You need to carry out algorithm twice and between them rotate the up face necessary number of turns.

R ud R ud R ud R ud
c) or one pair is turned wrongly. Such situation is called parity and it isn't possible in the cube 3x3. r2 B2 - back side rotate U2 l U2 r' U2 r U2 F2 r F2 l' B2 - back side rotate r2

If 3 of your pairs are turned wrong, just carry out both algorithms (for one pair+for 2 pairs=algorithm for three pairs)