Calculators: What to Look For, What to Buy
Many schools now require calculators. This site is not the place for a discussion of the problems (financial and otherwise) that this can cause, or of the "philosophy" on which these policies are often based. If you are interested in the politically-incorrect side of this issue, visit Mathematically Correct. (And for an interesting discussion of the value of a broken calculator, try here.)
But if you are wondering which calculator to buy, the following is my advice.
Scientific, business, etc, calculators
If you are looking for a "scientific" or "business" or "statistics" calculator, then there are many affordable options available to you. You can find cheap calculators at office-supply stores, discount department stores, and electronics stores, among other places. I have only one specific recommendation: make sure that the calculator has a fraction key; it usually looks something like this:
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This is a very helpful key, and will speed up fraction addition, simplification, and conversion.
Graphing calculators: Texas Instruments
If you are supposed to get a "Texas Instruments graphing utility", then you would probably want one of the calculators from their line of TI-84 models. The TI-84 is an update of their TI-83 which incorporates additional capabilities (increased memory, computer connectivity, default apps, etc) but which is backwards compatible with the TI-83. That is to say, the TI-84 will allow you to do more, while still remaining largely keystroke compatible with the TI-83 that your teacher is using.If you are supposed to get a TI-83, you might want to look at spending a little more to get the TI-84.
(Note: There are some slight differences in the models. For information, try here.)
However, the TI-84 seems
to assume that you have reliable access to a newer computer. Much of the
manual is accessible only through the CD that comes with the calculator,
calculator-to-computer connectivity relies on USB ports, and you may need
to download and install at 23-meg Micro$oft program (.NET Framework) to
get the computer side of the calculator to work. You may also need to
upgrade your browser, since the TI-84 appears to require Internet Explorer
6 or newer. So I would recommend the TI-84 (over the TI-83) for the updated
capabilities, but only if you have ready access to an updated computer
and a good Internet connection. (Note: I have heard, from experienced
users, that installation and use is not always problematic. The above
warnings reflect my personal experience. As they say, "your mileage
Do NOT get a TI-92, nor its update, the Voyage 200, unless you have verified that your school allows them; many schools are banning them. For some reason, though the TI-89 has many of the same capabilities that are getting the TI-92 / Voyage 200 banned, the TI-89 is generally allowed. However, it would still be a good idea to check first. Note that many (most?) instructors, especially at the high-school level, don't know how to use the TI-86, -89, or -92, or the Voyage 200, so you'll be on your own when it comes to learning how to use them. And their owners manuals tend to be the size of small textbooks.
If the only specification is that you are to get "a graphing utility", then the choice is up to you. Many companies produce perfectly nice calculators, but textbooks and teachers usually push the Texas Instruments TI-83 or -84. If you're willing and able to read the manual for yourself, then get whatever calculator you like. Otherwise, stick with Texas Instruments.
If you do get a TI-8X calculator, learn where the "convert to fraction" menu item is (this varies from model to model; check your manual). The command looks like this:
This command will convert the last value to its fractional form, if possible. It's a very handy command. If you have the "Custom" menu option, you might want to install the "convert to fraction" command on your custom menu, for convenience sake.
(By the way, if you already have a TI-85, and would like to have the "TABLE" feature that the TI-82, TI-83, and TI-86 have, use my "Table" program. The page in the preceding link contains the program as a text file; you'll have to type the program into your calculator yourself.)
Graphing calculators: Final thoughts....
If you are thinking of getting a Hewlett-Packard (HP) calculator (graphing or otherwise), see if you can find a friend or a fellow student who will let you borrow one. In my experience, people either love HPs or they really, really, hate them, and it would be a shame to spend a couple hundred dollars just to learn that you're one of the folks who hates 'em. They slice, they dice, they whistle "Dixie", but they might not be your cup of tea. Take a good look first.
In "real life", any of the scientific (or business or statistical, etc) calculators will serve most needs. Unless you're going into courses where graphing calculators are expected, a cheap calculator that has trigonometric keys (the "sin", "cos", and "tan" keys) should have just about anything you'll need. But graphing calculators can be nice, even in "real life", for much the same reason that some of us old-timers liked adding machines with a printout: the screen on a graphing calculator can display more information and, in particular, can make it easier to find one's mistakes. So, for instance, I tend to use a graphing calculator to balance my checkbook.
There is one other consideration: If there is no specification regarding which calculator you should get (or if you are given a list of models from which to choose), and you are planning on entering a scientific field of study at your college or university (math, engineering, or physics, for instance, as opposed to Poly-Sci or French Lit), then you might want to contact the appropriate departments to see if those departments have their own preferences. Be forewarned: It is entirely possible that you will be required to buy multiple calculators: one for the math department, another for the physics department, and yet-another for the engineering department. Calculators are very trendy, but the trend-oids don't often think about the real-world implications of their policies.
There; now ya know: I'm politically incorrect.
If you have lost the manual to your Texas Instruments graphing calculator, look into downloading a new copy from the Texas Instruments' site. The guidebooks are Adobe Acrobat documents, and fairly large ones at that, so you might want to download the manual one chapter at a time if you have a slow or twitchy connection.