Can I insert the page number of a specified bookmark into a Pages document?
Interesting question! I checked the Add bookmarks and cross-references in Pages page and couldn't find anything that would achieve what you want.

I then turned my attention to MS Word, thinking that if I could find a way to do it in MS Word, perhaps then I could adapt it to work with Pages.

The good news is I've found a way to do what you want in MS Word, but the bad news is I haven't been able to replicate this in Pages. So as it currently stands I don't think this is currently possible in Pages.

I would recommend you provide feedback via Apple's Pages feedback page (Note: You can also access this from: Pages > Provide Pages Feedback.

Cross-referencing bookmarks in MS Word

In the interests of perhaps helping someone else come up with a solution for pages, (and in helping users of MS Word), here's how I achieved this in MS Word:


Create your bookmarks as usual
Add your links to your bookmarks throughout your document
Now, let's say you have a bookmark called Diagram7 that's on page 10 and you're linking to that from the words "see Diagram 7" in a paragraph on page 3. To create your cross reference you would do the following:


place your cursor after the words you're linking from
now go to Insert > Cross-reference... to bring up the Cross-reference window
select Bookmark for your Reference type
select Page Number for your Insert reference to
select the Diagram7 bookmark in your list of bookmarks
click on the Insert button

Now the page number will be displayed at the location your cursor was at


NOTE: Just like other fields within MS Word, when the value changes (e.g. the diagram moves to page 12, so the value needs to change from 10 to 12), you will still need to use the Update Field option as normal to update the values displayed.