$pi is virtually useless. For whatever reason, mIRC has decided to display 21 digits for $pi. Well, $calc can't handle 21 digits. If you type $calc($pi) you can see mIRC quickly trims it to 7 digits. Meaning, if you need pi your best bet is to just do alias mypi { return 3.141593 } rather than use mIRC's built in $pi since it will make things slower since each time it is used it has to be rounded.