How to batch rename with regex patterns?

I’m using the batch rename and want to change a number if it’s followed by a letter. I can’t work out how to capture a pattern and use it. Any ideas:

I want:

Claim_Dropper1A
Claim_Dropper1B
Claim_Dropper1C
Claim_Dropper1D

to become:

Claim_Dropper2A
Claim_Dropper2B
Claim_Dropper2C
Claim_Dropper2D

Something like Claim_Dropper1[A-D] but I’m not really sure.

Try a dollar sign in the replacement pattern ($1), instead of a backslash (\1). The backslash version (\1) is only for when you want a backreference inside the search pattern.

So, your replacement pattern should be 2$1.