How do I create a formula for Column B to add a prefix to the value in column A?

JoshuaEllison 

Let's say the names begin in A3.

Enter the following formula in B3:

 

="RED-"&A3

 

and fill down. If you want to be able to fill beyond the last used cell in column A, use

 

=IF(A3="","","RED-"&A3)