One way:

Assume your list is in column A. In an unused column (say, B) enter

B1: =A1 & "A"

copy B1 down as far as required.

Select Column B. Copy it. Select Column A. Choose Edit/Paste Special,
selecting the Values radio button. Delete Column B.

In article ,
Gazivaldo wrote:

I have a column of over 2000 cells which I would like to alter by simply
adding a letter to the end of the text already in the cell i.e originally
"Coach 100" changing to "Coach 100A"