You run inot him at least once a week ? At the next opportunity try saying By the way my name is XXXX I'm in appt 23C, and wait...say nothing more. If he's got more than a grade 5 education he'll give you all the info you're looking for...
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At some point after that suggest coffee (together). That should get the ball rolling...
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-Carlos..
Angie's my introduction...

Hmmm. Okay, I have dated a couple of guys that lived in the same complex as I do. One guy, it was okay because he lived in a building I could not see from my place. But when I dated the guy across the hall, it was a nightmare. He would be waiting in the window for me to get home from work. And then he would call or knock on the door five seconds after I got home.....
How about this... next time you are talking to him, tell him you are starving and ask if he wants to go get something to eat. Or just talk to him, and ask if he'd like to get a cup of coffee sometime...

You know which mailbox is his???..Drop a piece of YOUR mail ... into HIS box...
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Maybe he'll be kind enough to return it in person??? ..
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But make sure it's a something that clearly indicates your appartment number, maybe like your victoria secret catalogue ... oh wait ... he might just keep that lol...
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If that doesn't work, at the next run-in, do what Carlos' suggests and ask him for coffee...
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Angie..
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Carlos fills my mailbox..

Angie's idea for dropping the catalog in his box was a good one. But next time you see him introduce yourself, and invite him to the fun party you are coincidently having that week...

It always helps to look for clues: does he wear any sports jerseys or band T-shirts? Any tattoos? Have you seen any bumper stickers on his car? Those can always provide conversation starters. Also, everything the other people said...