I'm not sure of whether or not I should waste 150 dollars to buy one of the most powerful calculators released by TI, the Ti-89 titanium. For all of you who own one or knows someone who does, how is it?? Right now I have a Ti-84, but I don't think it is as efficient as a Ti-89.. And yes, Ti-89s are allowed for the SAT Is, IIs, and most of the other tests. So, what will it be? Should I get one or not?