Asking, "What's your Zeta number?" would be proper within any chapter, but we would be more likely to ask among ourselves, "What's your Beta-Nu?", and not even bother saying the word "number".
BTW, most folks leave out the hyphen when writing, which is usually not a problem until someone's chapter ends in "Zeta", for instance Epsilon-Zeta (North Dakota). Is it Epsilon Zeta (U. Penn) or Epsilon-Zeta (North Dakota)? Marshall is a killer! Is it Zeta Zeta or Zeta Zeta Zeta????
Hahaha...
ZAX,
Jono