formating and limiting number of duplicates to less than 3

[radio900]

in excel 2007- how do I limit the number of duplicates in a column to 3?
tia

 

[Robert Mika]

Hi radio900 and wecome to the board.

If your data are let say in range A1:A40,
Highlight this range, go to:
Data Validation-->Custom and in the formula field enter:
=COUNTIF($A$1:$A$40,A1)<4

 

[radio900]

thanks for response
I need to limit the use a word in the A column,but if there are 5-10 say I want to keep 3 max. Iy's a big 20,000 entry data base. Sorta like eliminating dupes,but not all