<p>I’m using an 84 Silver in BC Calc and I’m fine. My friend is using an 83 and he’s getting by as well. I don’t think you’d be at a severe disadvantage if you didn’t have an 89. On the AP test, all the calculator functions for which you don’t have to show work can be done on the 84 (as well as the 83), so you’ll be just fine. Good luck!</p>