<p>it’s easier to get used to the 84, but the 89 has far more capability, especially in calculus (it does derivatives and integrals for you :p)
OP, time is a big concern on SAT Math Level 2…one of the biggest problems students have with time is checking over their work while they’re going through the problems. Most of the time this is unnecessary and chews up time…so tell your son to check his work at the end, not the beginning. Just make sure he doesn’t take that as a signal to work through carelessly; the best thing to do is to work carefully but efficiently through every problem.</p>