Rename some columns by adding a prefix

1. Create a list of the columns you want to prefix
2.  List.Transform => create a "Rename List".
3.  Table.RenameColumns

Code Example:

let
    tbl = Table.FromColumns(
        {{"a","B","C","D","E"},
        {"F","G","H","I","J"},
        {"K","L","M","N","O","P"},
        {"Q","R","S","T","U"},
        {"F","G","H","I","J"},
        {"K","L","M","N","O","P"}}
        ),
   
    #"Columns to Prefix" = {"Column2", "Column4", "Column6"},
    Prefix = "Old.",
    Renames = List.Transform(#"Columns to Prefix", each {_, Prefix & _}),

    #"Prefix Some" = Table.RenameColumns(tbl, Renames)
in 
    #"Prefix Some"

Before

After

Probably, which columns?

Please provide sample data.

Guys, you are awesome.