how to add sequential numbering as prefix to file names

Hi, I want to sequentially number files in a folder automatically in a batch process whilst retaining the existing file names. For example:

Document about cats.pdf

Document about dogs.pdf

Document about frogs.pdf

becomes:

01.Document about cats.pdf

02.Document about dogs.pdf

03.Document about frogs.pdf

Is this possible?

ive tried the bates numbering but that's not given the required outcome.

thanks.