setlocal enabledelayedexpansion

for /f %%i in ('dir/b *。 pdf’)do(

set /a n+= 1

Ren "%%i"! n！ %%i "

)

If you need to sort according to certain rules, the above directory can be replaced by

Directory /b/od or directory /b/o-d is sorted by date.

Directory /b/on or directory /b/o-n is sorted by file name.

Sort by file size.