If you read an ePub eBook on a nook and you read the same ePub on a Kobo, you will have the exact same page numbers as they both use ADE page numbers. If you read an ePub converted to kepub (via Kobo's store or a Calibre plugin) then you don't get page numbers that make the nook at all.
Kindle page numbers do not match Kobo or nook.
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