Calculators Are Important To Engineers

Every engineer has his or her idea of what kind a calculator an engineer should use and which are the best. Some old-fashioned purists feel that anything more than a little four-function, wallet sized calculator is too much. Others feel that only the latest and greatest number-cruncher is worth having. I suppose I am somewhere in the middle. I think that having a decent machine is time saving, but understanding the numbers and having a feel for what is coming out of the pretty box is important, too.

I have several calculators I use, but I consistently use Algebraic notation calculators. People who use RPN calculators are pretty crazy in my opinion. For people who have no idea what the difference is, the explanation requires some sort of mathematical understanding. It’s simply two very fundamentally different ways of doing the very same thing:

Algebraic calculators use the very same algebra that you learned in high school. Enter 1 + 1 and hit enter to get 2. RPN works in, well, the reverse: key in 1, then hit enter. Next key in 1 and hit + and the calculator adds this number to the last to get the answer 2. Thus, I use Algebraic calculators because they are closer to what I write on paper or enter into a spreadsheet.

The TI-30X IIS Scientific  Calculator. Courtesy of

My application to sit for the Professional Engineer exam was recently accepted by the state board. I happened to look up the NCEES site about their calculator policy. It was once that you couldn’t use calculators with a keyboard (why I stopped using the TI-92 before the FE exam), and then later that you couldn’t use a graphing calculator at all. Now, they limit the type of calculator to just six different models. Two each from HP, Casio, and TI. Therefore, I have bought a new calculator to add to my collection just for the exam. Don’t worry, there’s no racket to this. These are all sub-$50 calculators (actually, all but the fancy-schmancy HP 33s are less than $20). It’s just insane that I have to buy a new, less capable calculator each time I take a damn exam! I suppose when I take the SEII in a few more years, I’ll be forced to use a slide rule, unless you cheat with those. Then it’s time to break out the abacus.

So, I bought a TI-30X IIs, which is quite nice in that it has two lines in the display. One for the entered formula, and the next for the result of the formula.

Two Line Display On The TI-30X IIS.

The TI-89 Graphing Calculator, with the sporty transparent blue cover. Courtesy of

My main calculator is a TI-89. This little giant was a great asset on the F.E., let me tell you. I know I could have passed the exam without it, but it definitely shaved some minutes off of what could have been some pretty hairy problems.

It has all the great graphing features and such, but mainly I use the very simple symbolic algebraic and calculus solvers. They come in very handy when developing some formulae for use in engineering work.

The TI-92 Graphing Calculator, once the powerhouse of the calculator universe. Courtesy of

Before the 89, I used a TI-92, which oddly enough was the 89’s predecessor. This thing looks more like a lap-top computer than a calculator, but is very powerful. As you can seee here, it has a QWERTY keyboard and a huge screen.

I actually used a TI-35X, which is just a basic scientific that I bought my Sophomore year in high school through my first three years of college. This must have been a pretty fancy calculator when it was first introduced as the TI-35 Slide Rule back in 1979. To be honest, this is probably more than most engineers need to do 99% of their work. A whole lot of engineers I know use those little $2 things that you’d just through away as soon as the batteries died. My little 35 was with me everywhere until it was finally sat on by a friend, who then as a gesture of good will, bought me my first Hewlett Packard, an HP 20S (which was totally not necessary, I got all the use I could have ever hoped for out of that old thing). You can see in the picture that the display is what took the brunt of my friends rear end, although the calculator actually still worked for a long time. You just couldn’t read the display.

L to R - TI-35X, TI-92, TI-89, and HP 20s

Some Calculator History

These are some interesting sites on the development of the calculator: