Texas Instruments' Motorola 68000-based TI-89 provides a built-in computer algebra system akin to computer software such as Mathematica and Maple. It can simplify mathematical expressions and perform partial fraction decomposition, which is useful for some intermediate calculus classes. Basic algebra, systems of equations, limits, derivatives, and integrals are also possible, and can be performed symbolically. It can plot most anything including 2D, parametric, polar, and differential equations. Unfortunately, it is too powerful to be allowed on the ACT exam, although it works for the SAT and AP Calc. It's a little more expensive than the others, and if you're not past the ACT, you probably don't need a calculator this advanced. The TI-89 does support USB for downloading programs.
This calculator is probably the most popular in the K12 system, right along with the TI-83. The TI-84 offers some minor improvements over its younger brother: a USB port and clock functionality. It has slightly faster processing as well, due to a higher speed Z80 CPU. This popular calculator offers 2D, polar, and parametric plotting. It does not have a computer algebra system, so don't expect to be able to perform anything symbolic like simplifying equations, at least without external software that can be downloaded. On this calculator, finding limits, derivatives, and integrals can only be done graphically, not symbolically. It can do slope and definite integrals only with limited non-symbolic accuracy, so it probably can't help you with most true calculus homework. Of course, plotting is helpful. This calculator can be used on the ACT, SAT, and AP Calculus tests, among other standardized tests listed at the TI website.
First, we'll warn you that if you don't like a lot of features, this model is not for you. With the EL-W516T, Sharp has reinvented the concept of the scientific calculator. It displays four lines of text and shows entered expressions in condensed textbook form. It sports over 530 scientific programs and four programmable macro keys. You can even solve algebraic equations. The EL-W516B is hybrid battery/solar powered. At well under $20, why bother with anything else?
The HP 12c is one of the easiest to use advanced financial calculator available on the market. The large layout of the buttons makes it ideal because it requires less searching for function buttons, thus making you more productive. According to the CFA institute, the 12c is one of only two calculators that is allowed during the CFA exam. The large 10-digit display is easy to read and provides large LCD numbers, which can be either a positive feature or negative. Some of the competition features a two-line display, which makes doing calculations somewhat easier, but the layout of those machines are often a hindrance. The HP 12c has over 120 business and finance functions such as, amortization, cash flow, bonds, loan payments, and more. The downsides? The 12c has a higher price than a lot of the competition.
This Casio unit has all of the typical functions of a basic calculator; addition, subtraction, multiplication, division, with memory, square root, percentage and the like. But the best selling point here is the ease of use for those with less than perfect eyesight. The LCD display is bigger than many standard calculators and the unit comes equipped with a large, easy to read keypad so you can push the right button with confidence. The unit functions on dual power sources and offers all of the standard mathematic functionality you'd expect from a simple calculator. The calculator has an OFF button as well, so you can shut the unit down knowing you're conserving battery life, instead of waiting for it to power off on its own.