A usual way of predicting SAT was to add a zero to the PSAT score. Pretty "spot on" for son. With the new version of SAT though, don't know if that will still hold.
You don't have to add a zero any more. The new PSAT score is the same as you would have received on the SAT on that day with those questions.
Son was disappointed that he didn't do well on the algebraic stuff. He's been in an advanced math program since elementary school and hasn't worked with basic algebra since 7th grade. Did good on the advanced math portions though. He and his classmates in AP statistics broke down the scoring yesterday and he estimates his score would have been about 100 points higher if he had aced the algebra part. I don't even know where to begin to do that type of analysis myself, so I just nodded my head.