You could make brackets so you can do more complex mathematical equations. But that would be far too easy and a waste of your time. Theres nothing more I think you can do to a calculator. That is a calculator. Can't add anythnig more to it, and anything else you could add to it would be easy.
Try making an rs experience calculator based on this equation:
Heres a javascript version if taht's easier for you.
<SCRIPT LANGUAGE="JavaScript">
<!--
document.close();
document.open();
document.writeln('Begin JavaScript output:');
document.writeln('<PRE>');
points = 0;
output = 0;
minlevel = 2; // first level to display
maxlevel = 200; // last level to display
for (lvl = 1; lvl <= maxlevel; lvl++)
{
points += Math.floor(lvl + 300 * Math.pow(2, lvl / 7.));
if (lvl >= minlevel)
document.writeln('Level ' + (lvl) + ' - ' + output + ' xp');
output = Math.floor(points / 4);
}
document.writeln('</PRE>');
document.close();
// -->
</SCRIPT>
My challenge to you :p