F2L 30
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
R U R' U' R U R'7 moves · R and U only
Alternatives
U' R U2 R' U2 R U R'8 moves · R and U onlyU2 F' U F R U R'7 movesU' F R' F' R2 U R'7 moves
How to recognise it
Corner in the slot with white facing right; the edge is on the right of the top layer, its side sticker matching the right centre.
Its inverse is another case
Do the 30 algorithm backwards, R U' R' U R U' R', and you are solving 27.
That's why CubeDojo never scrambles 30 that way: it builds a random state with the case fixed, so you practise 30 and not 27.
Practise 30 now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.