how to create a separate number next to page number on master page?

Hello there,
So on my master page, I was able to do the page numbers on my footer, Page A of 1 so it increases based on the page. But on the right side, I'm needing to increase the number by 1 in the box. So D100, D101, D102, etc.
I'm having a really hard time figuring out how to increase this properly so that it doesn't impact the page count on the left side. Any help would be appreciated.


