Teacher also didn't know if they really calculated or not, hence the reason why they need to show the Method. I recenly teach my Cousin a bit Math so i know teacher feeling when student didn't include the methode. In National test and school test though. They didn't need to write method.
"i know the answer, it is just i can't tell you how i achieve the answer."
if that magic also gives instant understanding of the concept, it would be nicer...
Fuck. It's like being told; "Well, you got the right answer but you didn't show your work, so I'm going to have to give you half marks for that."
Fuck off