I'm using Goodnotes for giving university lectures. It works well in many ways, but I was surprised, to say that least, to discover you can't add page numbers. Such an obvious and useful (and, one would think pretty easy) thing, and pretty frustrating to live without. It should just be a standard template part.

Page numbers would make printing a specific page from a notebook more efficient.

I totally agree! When creating a new notebook, it would be great if all the pages where numbered (per default).

It would be really helpful. Choice should be to display it in the toolbar or on the paper. If on the paper, one could choose the font and position -- e.g.:
- horizontally: distance (number + choice of units) from (left edge, center, right edge);
- vertically: distance (same) from (top edge, middle, bottom edge).
Enhanced features:
- parametrizable prefix (e.g. "P. ");
- option to display the total number of page (e.g. 1/23);
- starting number.

This function is really really helpful. Or else I will have to rely on my "paper" notebook to make it easier pacing my steps.

I agree as well. It's a pain right now to have to check the thumbnail view to see what page you're on and how many pages are left.

I definitively agree...
It would be super helpful to know how far along we are during a lecture and how many more slides left without needing to scroll to the very end of the file! n

Here is what I would like to see. Of course, I don't have the final say, but I would really use the page number feature.
https://www.dropbox.com/s/61ag7nppet43c0t/Photo%20Jan%2023%2C%2010%2049%2029%20AM.png