Mandarin Chinese (#21E)

This is my first attempt at using a rhetorical question in Mandarin Chinese (a.k.a. Putonghua).

I didn't learn this from any of my lessons. I just put it together based on what I already know. Grammatically it doesn't make any sense, and I doubt it would be understood the way English speakers would understand the rhetorical phrase, "Don't you know it," but, literally, in Chinese this final phrase translates as, "You don't know, yes or no?"

My wife and I have nine kids. We have daughters, and four sons.

Your family is big. Your family is really very big.

Correct. Don't you know it?!*