this sort of thing comes up fairly often. The 3/4 part of an address may be the garage - a rear bedroom - who knows? Certainly not the guy at the front door who answers my knock and says he never heard of that number! Sometimes a person wishing a "secret address" will just concoct a fractional number with the hope that the postman will deliver to the main mailbox at the house and someone holds the mail for Mr. X. The post office requests that all mailboxes in L.A. show the house number(s) where mail is to be deposited but sometimes they don't get so particular.

(Fortunately, California process servers are allowed to deliver to an address "where mail to the defendant is regularly received," so I could sometimes sneak a peak in the mailbox to see what's in there. Never found a bobble-head, though. That would freak me out!)