yes, you can divide numbers. there's nothing wrong with the way you're doing it. there's just something wrong with str_for_num, i'd assume, or the way you're using it, but i can't tell with what little info i can see from here. my personal recommendation is that when you want to see the output of a variable, make a panel use the variable, not a string, unless you want to write to a file or have typed user input or something. strings can be quite frustrating or tedious, and from what i can see you don't need to use them.
julz