I would go to the Saxon Homeschool site and have him take the placement test. Many kids can skip 8/7 and go directly into Pre-Algebra. Saxon has all the info about that on their website (or they did when I checked a year or so ago.) We don't use Saxon but I researched it for the future (although at this point, we're leaning another direction after we finish Horizons 6).
Definitely do a placement test I agree with the previous post. My son just finished Calvert 4th grade math, and due to finances, we aren't able to go the Calvert route this year. I had him take the placement test, and he placed in 6th grade math. Unless you have used Saxon Math all along, take the placement test. It is easy and free, and you grade it yourself so there is no waiting involved. HTH! Tara
well I used that last year for my dd and she didn't like it at all so we went to TT Math this year and it is going wonderful, what a big different. What she didn't like about it is never had enough problems for her to work out. Never explain well she said. But, we love TT alot.