I write this instead when I type exponents : x^2 (how about thirteen cubed?) 13^3
This has been accepted by every teacher I have had so far. I guess you could go and find some way to type superscripts, but I think that only works in new word document programs, not just on your keyboard. I never bother really. Try character map too, that should be in your computer's accessories -where you can get all the accents and symbols and whatnot.
I hope this helps! :-)