Debra, here is one solution, assuming you want the total in days. (Oh, yes, I believe that your dates should be en columns D and E, instead of columns A and B, as you posted):

On your spreadsheet, in an empty column. say, F:

In F10, enter:

=DATEDIF(D10,E10,"d")

and copy down to the last cell you need, say F30.

In column C,:

In C31, enter:

=SUM(F10:F30)

Does this work for you?

P.S. To Whoever Reads This:

In my Excel 97, the DATEDIF() function works well. But, I didn't find it listed in the fx place, nor in the HELP place. I have all the Excel-furnished addins installed, but no additional ones. How is it that the function works, but I can't seem to find it as an available function?