To quote previous answers to the same question ............ you will have to calculate it yourself, on your own sample, because every piece of paper will have it's own resistivity.
To help you find the method if you do a Google search for "resistivity of paper" you will find plenty of guidance.
An estimate is at 10^9. If you're still stuck for a technique for your plan (I got to do it tonight too) look into the wheatstone bridge, thats what I'm writing about for the next few hours. Good luck with the practical tomorrow