The page numbers are the same for all Adobe Digital Editions devices. The algorithm is complicated, from Adobe's EPUB Best Practices Guide:
The approach used is the following:
• Determine a compressed byte length of each resource which is referenced in the spine, subtracting any known encryption overhead (IV size)
• Assume that there is a page for each 1024 bytes in each resource, rounding up to the nearest whole number of pages for each resource
• To map page breaks into a resource, use the number of pages for the resource as determined in step 2, count the number of Unicode characters in the resource; distribute synthetic page breaks in the resource evenly between the characters by dividing the number of characters by the number of pages; if the number of characters don’t divide evenly among the pages, round the number of characters per page up and let the last “page” contain less characters than the rest.