This is unusual to number paragraphs and restart them relative to the page they sit on rather than the logical structure of the content. You would need to reset the content continuously with any changes in pagination which is a continuously repeating process.

Are you sure you don't really want Line Numbering? This can be very simple to implement and will be much more robust in restarting on each page. See How to Add Line Numbers to a Microsoft Word Document

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Andrew Lockton
Chrysalis Design, Melbourne Australia