[nuggetsyl]

Well lets take an average processor speed, not too fancy, cracking approximately at 22,004k/s a PDF document. Assuming you are only bruting a-z0-9A-Z with out spaces, special characters, etc.

It would take approximately 1 septillion years. or 1.0306281275164522e+24 years 33 days 7 hours 30 minutes and 54 seconds

The amount of password combinations you would potentially have to test is (7.159713505559651e+35 password combinations)

Again I am assuming we are NOT using any GPU, Amazons AWS, etc. We are using an average processor. If you use GPU or AWS, this would SIGNIFICANTLY speed up your cracking. You can play with the numbers at this. http://calc.opensecurityresearch.com/