How do I display page numbers in a book?
You can add simple PHP code in your node.tpl.php

    &lt;?php
      $allbook = book_toc($node-&gt;book['bid'],3);
     $allbook_chapter = array_search($node-&gt;book['mlid'], array_keys($allbook));
print $allbook_chapter;
            ?&gt;


This code prints page number of current node. This in't better way of course. 
Moving this logic to template.php is better solution.