Enter the “Number of Links From Each Page” that links to the page in question to get a Page Rank estimation. For example if 5 “Page Rank 4” pages link to your page, then put 5 under “PR 4”.
Optional: You also have the option of changing the “Average Number of Links Per Page“. If all of the pages that link to you have 70 total links on them, then you should change the “Average Number of Links Per Page” to 70. If you are unsure then leave it at 40.
http://www.thinkbling.com/prcalc/