This works for me, using the fraction 7/13 with Word 2003:
- Type the fraction 7/13
- Select the number 7; click Format > click Font
- In the Effects section, check mark Superscript > click OK
- Select the number 13; click Format > click Font
- In the Effects section, check mark Subscript > click OK
Take a look at my website
http://msword.mscomputertrainer.com for more Microsoft Word tips.