When the “Current Page Number” placeholder sits on a master page, every page to which you assigned that specific master page will display this variable – the number will change automatically on every page. If you change the style assigned to the placeholder on the master page (let’s say you set it to bold), all page numbers will update to that style (all numbers will become bold).
One of the last things we need to do is our Table of Contents. We did this earlier, where we had different page numbering. So, all we need to do now is, because we've redefined all our Styles, and we're doing it all proper now, if we go to 'Layout'-- I've got my cursor flashing in here, first of all go to 'Layout', let's go to 'Update Table of Contents', and I'm going to click 'OK'. There's some spaces left in the front of this when I was messing around with it before, yours should be fine. So it's updated to the correct numbers. One thing I also did was I went in and adjusted the font from Medium to Light because I just liked it. I did that in between tutorials.
Changing the numbering display affects how pages are indicated in the InDesign document, as in the Pages panel and in the page box at the bottom of a document window. The numbering display also affects how you specify page ranges when printing and exporting the document. However, the numbering display does not change the appearance of page numbers on document pages. numbering in indesign