Originally Posted by zamana
Kindle books are ONE BIG HTML page. The only difference is that instead of scroll up/down, you scroll left/right. So, it doesn't make much sense to me the concept of page numbers. If you change the font size, the book will grow up our shrink...
Am I wrong?
You are correct, but some (older) e-readers counted how many characters/words you'd be able to fit on screen, and how many characters/words the book actually had. Then you'd see the number of pages (or, more correct, number of screens) to read become more or fewer, as you increased or decreased the font.
Calibre can now do page estimates; a page does not have to be one screen. I'd like to be able to display the page number full time, but alas, that's not possible.
Amazon books have page numbers built in: with them, a page can be longer than one screen. They base the page numbers on the last paper version that was available when the ebook was created.