Add sequential numbers


I’m just wondering if there is a way to add a sequential number to a texture automatically?

To explain. I need to texture a number of items, let me take the light switches. Now each of these switches have an individual TAG number/Name so instead of me having to changes this in a manual way is there some form of this been done by some instamagic formula?

It could be that it could take the number from the mesh name. i.e. if I call the first mesh “light-sw-0001” if I then replicate this within UE4 I would light the others to be “light-sw-0002”,“light-sw-0003” and so on. Maybe this is something that I could/should do within UE4 but I thought I would ask in the Allegorithmic Substance forum too and see which is the best option.