renaming files in numerical order

[Voro]

This is probably a stupid question, but I cannot for the life of me figure this out

i have a bunch of files, named:

29981.pdf or 08.04.13 1.pdf (I dont know if this makes things easier but I can always rename the first file)
08.04.13 2.pdf
08.04.13 3.pdf
08.04.13 4.pdf
etc.

They are all invoices which need to be renamed to their respective invoice number. They are all in order. So if the first one is 29981.pdf, how do I get the rest to be named 29982.pdf, 29983.pdf, 29984.pdf, automatically.
I have tried figuring this out on my own, reading the manual and cannot find anything. Please help.

Thank you!

[Stefan]

Hi Voro,

please provide a comparison like

OLD name:
ABC.txt
DEF.txt

should become NEW name:
XYZ.txt
GHJ.txt



.

[Voro]

File1.pdf
File2.pdf
File3.pdf

Becomes

24780.pdf
24781.pdf
24782.pdf

I would choose the number it would start from.

[Stefan]

File1.pdf
File2.pdf
File3.pdf

Becomes

24780.pdf
24781.pdf
24782.pdf

I would choose the number it would start from.

FROM:
File1.pdf
File2.pdf
File3.pdf

TO:
24780.pdf
24781.pdf
24782.pdf

DO:
Remove whole old name and add numbering instead, starting at wanted value.

USE:
File(2): Remove
Numbering(10): Mode:Prefix, Start:24780


.