It was everyone guessing what the "curve" would be on the test which here is represented by the number of questions you could get wrong and still get a 170. It turned out to be a -12 "curve" so you could get 89 out of 101 and get a 170.
My Scantron sheet says "use black No2 or HB pencils only", so I'm guessing they are similar enough. The common wisdom of the internets seems to be that a "middle of the scale" HB is pretty much a 2, but none of the scales are truly standardized.
Wait is this expiration in reference to purchasing PTs through Cambridge? I've never had a problem with buying/downloading from Cambridge, but guessing I should buy the few PTs I haven't bought already?