Because a standard ePub is a reflowable file type, it is like one long document. As such, it essentially has no pages. Therefore, a book with 170 print pages will not have 170 eBook pages or even 170 frames. There could be more or less depending on the devices. EBook viewers and devices such as Adobe Digital Editions, Kindle, Nook, iPad, etc. assign numbers that appear to be page numbers. If the numbers seem off, there is no cause for panic. The numbers do not and are not meant to correspond to print page numbers. Instead, they are for readers to gauge their progress and easily find their place in a book.
A fixed layout ePub, however, is made to resemble the layout of the print book and is not reflowable. This type of ePub has page numbers displayed in the file that correspond to those in the print book. A device that reads fixed layout ePubs, such as the iPad or iPhone, still shows location numbers at the bottom, but they may not correspond to the numbers on the pages if the front cover and frontmatter are counted as pages. (For example, one could click on pages 6-7 on an iPhone and be directed to a page numbered 4 because the iPhone reads the front cover, title pages, copyright page, and ToC page are considered pages 1-5.)