Renumbering Files from a Selection of files from a group of files

I wuld like to add about 50 files to renumber and would like to select a few a time.
For Example
I have added 10 files to be re-numbered
1
2
3
4
5
6
7
8
9
10
Out of these I first only want to choose 1,2,3,4 and 5 to be renumber as 21,22,23,24,25
the next batch 6,7,8,9,10 I want to renumber as 31,32,33,34,35
How do I do this in one batch or do I have to do it separately.
I appreciate the help to learn how to do this if someone can support me. Thank you.

Reply to #1:

Hi Mariya,

Without using javascript, the only way I know to do this is like this:

(1) RENUMBER method:
Number position: 1
Change to: Relative to existing number
Number difference: 20
Zero padding: no padding
Apply to: Name
{if}
Field: Name
Match: relative expression
Pattern: ^[1-5]$

(2) RENUMBER method:
Number position: 1
Change to: Relative to existing number
Number difference: 25
Zero padding: no padding
Apply to: Name
{if}
Field: Name
Match: relative expression
Pattern: ^[1-5]$
Not matching: CHECKED

Screenshot: https://drive.google.com/file/d/1G9kM3C8z1iAvHaFGbgeZnXbqFsS 4a2cK/view?usp=sharing

It's probably easier just to drag what you want for each change, change it, then do the next batch,
but you asked so there you go! :)

Best,
DF