How to do math inside of a regex?

[Rossman123]

If I have "Tom owns 2 cats", how do I search and replace with a regex,
so that I get "Tom owns 3 cats" ? I want to be able to find a digit,
add 1 to the digit, and replace with the result. Thanks!

 

[Brian Wakem]

If I have "Tom owns 2 cats", how do I search and replace with a regex,
so that I get "Tom owns 3 cats" ? I want to be able to find a digit,
add 1 to the digit, and replace with the result. Thanks!

s#(\d)#$1+1#e