This annoyed me the other day whilst twinking, if your calculation resolves to 0, it says the format is wrong.... since 0 is classed as "empty". Not very important just might want to update SVN or something.

Need to change
if (!empty($result))
return $result;
else
return "Wrong syntax, please /tell <botname> <pre>help <pre>calc";

to

if (!empty($result) || $result == 0)
return $result;
else
return "Wrong syntax, please /tell <botname> <pre>help <pre>calc";