you dont need the halt and you seem to have a bracket mis-match maybe try...
on *:TEXT:!calc*:#: { if (!$2-) { .notice $nick 3,15Sorry, you didnt supply an equasion to calculate } else { .notice $nick 3,15Calculating $2- $+ ... 3,15 $2- = $calc($2-) } }
but nice work keep it up =)