Casio FX-300ES Scientific Calculator with 249 Built-in Functions, Black

As a math teacher of 35+ yrs experience, I feel that this is the best inexpensive calculator for any national standardized test. Although it is not accepted for the GED test until 2012, I believe the other standardized tests allow it now. The advantage is that this calculator gives the answer in the form expected on the test. For a simple example, given the problem square root of 2 times square root of 3, most calculators will give 3.464... , which will not be one of your choices. The Casio will give you square root of 6, which is how the answer will show up on the test. Not only that, but the Casio allows you to put numbers in just as you see them in the problems. Most calcs in this price range require you to enter operations backwards (reverse notation) such as 9, then square root, to get 3. On the Casio screen, your entries actually look like what you see on the page. Although it take a wee bit to get used to this, it is worth the effort. (I still prefer the TI graphing calculators over Casio, but this is the best scientific calculator under $20).

For 15 years, I have been using a Casio FX-300SA calculator, and I was always impresssed by its ability to work with fractions. This new version not only works with fractions, but when a problem does not evaluate to a whole number, the calculator will give you the result as a fraction, which you can convert to a decimal number with the push of a button, if you like. You can enter problems exactly as they appear in a test or textbook, with or without multiplication signs, and the calculator will give you the answer just as it would appear in the book. It handles exponents and roots of any index, and always gives you the result in a useful format. No more obscure numbers with 15 decimal places. For any price, this is the best calculator value on the market.