Sunday, December 16, 2012

Calculator Review: TI-30X IIS

Hello Everyone,

In my work as a math instructor and math writer, I am frequently asked what calculator is the "best" calculator. Although I hardly believe any calculator can be arbitrarily named "best", I believe that the Texas Instruments 30X IIS has the best combination of ease-of-use, utility and affordability and is the one calculator I recommend above all others.


 Although the picture above will link you to (one of) the product (pages) on Amazon, there are a few different versions available (seemingly all from Texas Instruments) and depending on the color/product page, the price may be different by $2 or so! It can generally be found between $10 and $20 and is available in stores as well.

 One thing you need to be careful of is to not purchase the TI-30X IA. In my opinion, this calculator is little better than a basic adding machine, but looks similar and has a similar name to the TI-30X IIS.

The thing that really sets the TI-30X IIS apart from its competitors is the 2-line display. What you enter will show up on the screen, and you are able to see the sequence of mathematics before you press the final "enter". Thus, when you get a result that seems odd, you are easily able to arrow up to the screen and review what you've entered for errors.

Additionally, this has the nice result of the math entered into the calculator is the same as it would appear in print when working out a problem.

The calculator is reasonably powerful and has most functions an advanced math student would use including logarithms, xth roots, e, and the trigonometric functions, their inverses and the hyperbolic versions as well. For astronomy students (or engineers working with angles), the calculator does have degree-minute-second notation as well and for scientists, it can output numbers in scientific notation.

It seems to max out around 10^99 for scientific notation (obviously rounding to about as much as it displays on the screen). This brings us to the one drawback in my opinion (although an understandable design choice), there is no way to distinguish between rounded values and exact values. You hope that when the calculator screen fills up with digits that it is an approximation and that when the calculator expresses a number succinctly that it is exact, but there's just no way of knowing. Anything past the ten-billionths place of displayed accuracy is not shown (or apparently remembered either).

This is actually probably one of the causes of it being so useful at such a price though. With the calculator limited to billionths, you can "overload" it by typing in more digits than this. Thus, 0.2222222222 is interpreted incorrectly by the calculator as 2/9. It is hard to fault the calculator for this however since you rarely need more than the billionths place of accuracy.

For students struggling with fractions, the "fraction" button is a godsend. The fraction button is what I call the button that looks like the mixed number "A b/c". If you press this once between two numbers it will interpret the first number as the numerator and the second number as a fraction and will do arithmetic normally with fractions (and display the answer as proper fractions, integers or mixed numbers too). If you press the button twice between 3 numbers, then it will interpret the first number as the whole number part of a mixed number, the second number as the numerator of the fractional part of a mixed number and the third number as the denominator of the fractional part of the mixed number. It can handle denominators up to and including 1000, but 1001 throws it for a loop, but if the number reduces to a denominator less than 1000, then it will automatically do this for the user.

A great additional feature is the robust statistical package that comes with the calculator as well. This one feature enables it to be the only calculator students need to buy for most of the classes that I teach (the exception being if students need graphing ability or additional statistical features). Although limited to a single set of numbers (either one variable with frequencies or two variable pairs), it returns most statistics students will need, including means, standard deviations (both sample and population), sums, sums of squares, slope of a regression line, y-value of the y-intercept of a regression line, correlation coefficient and predictor functions for x and y if two-variable statistics are used. Although I remember my first TI-30X IIS could only store ten data values, the one I currently own (it's blue) can hold up to 42!

Overall, this is one of the easiest to use calculators on the market with enough features to carry a student through a basic statistics course or calculus class (so long as graphing isn't required) and is ridiculously affordable when compared to some of the more advanced calculators.

Final Grade: A+ 10/10