"This is the book of anyone."
Translation:Asta este cartea oricăreia.
oricine (nom-acc) / oricui (gen-dat) = anyone (generic person, no gender, no plural!)
oricare = any (+ noun), any one (of concrete things/people)
oricare m./f., singular/plural
genitiv-dativ [(-a) unless before a noun, like acest(a)]
singular oricărui(a) m., oricărei(a) f.
plural oricăror(a) m./f.
The English translation is unnatural. An English speaker would say, "this is anyone's book."
Don't worry, Romanian sentence is unnatural too. Nobody will say "oricăreia", it is grammatically correct, but in 50 years i heard it maybe 5 times (mostly in grammar classes in middle school, and including this one here :))