Many ebooks, especially those in PDF format, retain their original pagination. You can check the top and bottom of each page as you read to see the page numbers if available.
If no page numbers are listed on the pages themselves, you can check the table of contents to see the page number associated with the beginning of each chapter. Starting with that page number, you can count to determine the number for the page you're on.
Some ebooks do not display page numbers in either place, so you may need to follow the guidelines for your specific citation style in order to cite an ebook source without page numbers. For information about citing sources, visit the Writers' Studio via Blackboard.