I have some advice for you.
First, it looks like you were, indeed conducting a breaching experiment to see if math jokes would or would not be entertained or appreciated. It's hard to say exactly, you provided screen shots only of the comments (which show many people voting to close) and most of us aren't able to see the question since the site is in private beta.
Second, please consider that some people just have blunt, if not abrasive personalities. That doesn't mean they are trying to be deliberately mean, or harsh, it just means they say pretty much whatever is on their mind. On very technical sites, you'll run into this quite a bit.
Your thoughts are worthless to me .. isn't exactly a productive way of ending an argument. It takes two to tango.
If you really feel like someone is being consistently abusive, flag them for moderator attention or e-mail firstname.lastname@example.org (suggest the moderator route first). But, be sure to check yourself and your own behavior as well :)
Sometimes, it's just better to not get in a debate. If the community wants your question, it will leave the question open. During the beta period, this is the kind of thing that should be discussed on the associated meta site.
I can see why some would have adverse reactions to that. If someone insults you, flag the comment and move on. Let the community decide if the question is appropriate. These kinds of 'experiments' are bound to annoy some people, and that is a consequence that you have to be prepared to deal with.
Finally, he was not calling you
stupid, he was referring to the question. A more appropriate response would have been no response at all, or (if you must):
@whoever - wow, that was a little
harsh. Noted. Lets see what everyone
else thinks of it, we're supposed to
be determining what is and is not
acceptable here and this type of thing
is bound to come up.
A little diplomacy even in the absence of the other party using it goes a long way.