Originally Posted by kentuckyslone

Your Page Rank is determined not only by the number of backlinks, but by the quality of the backlinks. For example, you may have 1,000 backlinks from PR0 pages and have a PR0 or PR1, but if you have a few backlinks from PR5 or PR6 pages you can easily have a PR4 or PR5 yourself.

This is just a general guideline not an exact method or science. Just remember that the higher the PR of a page that links to you the more valuable it is in contributing to your own PR. It is also important that your backlinks come from relevant pages. If you are promoting a real estate site try to get links on other real estate related sites.