To type the squared symbol, use the Alt code for powers, which is 0178. To do this, first make certain that the "Num Lock" is on, hold down the Alt key and type the numbers 0178. This will give the superscript symbol "2".
In either Microsoft Word 2003 or 2007 edition, a way to write a mathematical term like x2 is to use the Microsoft equation tool. By clicking on the "Insert" tab and then the "pi" symbol with the word "equation" beneath it, the equation tools should be displayed. Clicking on the script tab will display rows of symbols and tabs. Click on the "Script" tab and click on the x squared symbol listed under "Common Subscripts and Superscripts."
An alternative method is to use the "Design" tab instead of the "Insert" tab to access the equation tools.