Are magical exchange programmes possible in the Wizarding World? Would it be possible that someone from Ilvermorny comes to study at Hogwarts or vice versa? Like an exchange program?
Is there a such thing as an exchange program in Harry Potter? In the Harry Potter universe, is there any mention of an exchange student at Hogwarts or one of the Hogwarts students going on exchange at another school?  This happens all the time in the "muggle" school systems I'm sure it would happen in the wizarding schools as well.
Modular arithmetic: division, fractions, solving linear congruences I want to ask a question about modular arithmetic. I know, that modular multiplicative inverse exists only if modulo and integer are relatively prime. I want to know, are there any ways of division in modular arithmetic, if modulo and integer aren't relatively prime? I tried to find info about that, but failed.