http://www.microsoft.com/office/previous/excel/
Under Using Excel, select How-to Articles
Scroll down & select :
How to Count the Unique Entries in a Column of Excel 2000 Data
Review the process outlined here.
Page back to main page and select:
Scan the suggestions on this page.
Page back to main page. Under Support, select:
Select PivotTable Resource Center
and search for "Calculate the Amount of Time Between Two Dates"
http://www.mrexcel.com/index.html
This site is operated by a private individual who subcontracts out his expertise.
Search for the subject "excel" to retrieve full text books about Excel and Office.
rgause@mail.ucf.edu
(407) 823-2563
Last modified: August 26, 2002
http://pegasus.cc.ucf.edu/~rgause/classes/ccj3072a.htm