Page number across several documents

Hi all. In InDesign, how would I go about adding page numbers across a publication made up of several InDesign documents?

-This is for a very large advertorial quarterly publication (300+ pages)

-I'm just following the established process where each article is saved as a separate indesign file. In some ways, this makes sense for the way the publication works and accommodates "Grid" changes and ad sales. --When it comes to updating the pagination the previous Art Directors and designers manually input the page numbers into the parent page for that particular article. It seems fraught with potential errors and is unnecessarily tedious. Surely there must be a better solution? 

-please, any help from advanced InDesign users and publication/catalog designers would be much appreciated.