How to exclude data already used?

[Bill]

I am new with this program (excel2003). I like to play logic games and have a
big question. If I have a group of values (letters, names or numbers) and I
want to use them on a new row/column without using the same value twice, How
do I deduct, or exclude that value from being used again? Thanks you much

 

[Max]

One thought .. Try Debra Dalgleish's page at:
http://www.contextures.com/xlDataVal03.html
Data Validation -- Hide Previously Used Items in Dropdown