As far as I know, mIRC doesn't use it's own built calculator, but the system's calculator.
You probably don't know much then. Where do you even get your "facts" from? You could not be more wrong.
Hint: if you don't know an answer, don't reply. I know your OCD makes it hard for you not to type out every single thought you have, but please, for the sake of civility, stop.
edit:PS. this isn't a bug. Sure, it's the wrong answer, but its your script logic that is supposed to be responsible for guarding against "impossible" results like those. Infinity cannot be represented numerically, so 0 is substituted, because it makes the most sense (of other possible values)-- 0 or $null. This is an intended behaviour. If mIRC had exception handling, it would raise one. mIRC has :error, but that's really overkill-- most people probably don't want control flow to change just because they divided by 0. For most rational results regarding the world of IRC-- N/0 is "0". $null wouldn't be bad, I suppose...
