I feel like I just found a hidden gem!!
Incredibly hard to find, but necessary to know in order to identify pages to exclude from the “pages” sidebar widget.
1) Go to edit pages (from the drop down pages menu, on left, in your admin back-end) and MOUSE over each page link.
2) Look down in your browser tray to see the path and at the end of the path you will see a number. This is the page number!!
EXAMPLE: http://yoursitename.com/wp-admin/page.php?action=edit&post=81
I’m not sure if this works in earlier versions of WordPress, but it works in version 2.8.6.
Happy blogging!