Format the cell as Text prior to entering the data, or precede the number
with an apostrophe (the apostrophe will not display in the cell but will be
visible in the formula bar) or format the cells with a custom format of
0000.
--
Cordially,
Chip Pearson
Microsoft MVP - Excel, 10 Years
Pearson Software Consulting
www.cpearson.com
(email on the web site)