TI-83 Calculator trouble?

My TI-83 Plus is giving incorrect exponents. For example, I am trying to divide a number with an exponent of 8 by a number with an exponent of 15. As you may know, the answer should have an exponent of 8-15 = -7, but the answer shows an exponent of -8. Is there a setting or mode that is making this happen?
Update: The full problem is:

(3 * 10^8) / (3.289 * 10^15)
4 answers 4