in previous word's you highlight the number> format> font> select superscript under effects. Is there anything like that in 2007? sorry if its no help.
EDIT: Just looked at your screenshot, on the right click there is a *font* link, try looking in there?
exponents are easy guys. you are all killing each other on this ? lol
here's how it's done :
am assuming your number is already there, just go to Insert-->Insert Object
now browse for Microsoft Equation 3.0, some bunch of sh*t will appear, like below
just where my poorly created arrow is pointing is Subscript and SuperScript
when you click it it will give you a drop down list as to where you want to place your "power of"...