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After using a TI-83 Plus calculator for the last 5 years, I decided to upgrade to the TI-89 Titanium. This calculator is unbelievable in its features and power. First of all, it is more suited for advanced math, such as calculus and beyond. This calculator is NOT meant for high schoolers who are taking algebra, geometry or trig classes. If you don't know what a derivative or an integral is, then save your money and buy a TI-84 instead. (Besides, I believe most high school math teachers ban the TI-89 on tests) This calculator can also run programs in its Flash memory, which can be downloaded from the TI website. A USB cable is included standard. TI has made the newly designed sliding cover much more secure than the old TI design (TI-83 plus, TI-86, TI-89 regular), whose sliding cover was not very secure and became looser over continued use. The cover is very hard to get off the first few times (I was almost afraid of breaking it off), but over time it has gotten easier. Switching over from the TI-83, the only problem I've encountered is the operation of this calculator is very different from the 83. The menus are different, the interface different, different buttons. It takes a while to get used to.