F2L 40
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
R F U R U' R' F' U' R'9 moves
Alternatives
F' U' R' F' U' F U R F9 movesR2 U R' U R U2 R2 F' U2 F10 movesR' F R F2 U F U2 R U R'10 moves
How to recognise it
Both pieces are in the slot, with the edge flipped and the corner twisted so white faces you.
Its inverse is another case
Do the 40 algorithm backwards, R U F R U R' U' F' R', and you are solving 41.
That's why CubeDojo never scrambles 40 that way: it builds a random state with the case fixed, so you practise 40 and not 41.
Practise 40 now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.