On 15.09.2020 19:05, Arlen Holder wrote:

I just tested it, by the following process, which worked just fine:
a. I selected 75 photos in the Windows explorer
b. I right clicked on one,
Don't click on "one", but on the first one of the selected files,
because this one is renamed first and then all other files in the
displayed order.

and selected rename & typed "a"

Don't type "a" but "a(10001)" to get a proper sequence of file names.