Saturday, April 18, 2009


While my son Jason and I were shopping last week, he stood transfixed in front of the calculators. He has a few 4-function calculators at home, but he was amazed at the number of buttons on some of the more complicated ones He also thought it was cool how each button could do several different operations. There's really no reason a nine year old needs a scientific calculator, but I wound up buying him a TI-30XA anyway.

Growing up I was always fascinated by calculators, and I think it served me well - leading to a degree in Mathematics and a career in software. I figured if Jason showed even a fraction of the interest I had, that $10 calculator would be one of the best investments I'd ever make in his education. He opened it up on the drive home, anxious to know what every button does.

How do you explain hyperbolic cosine to a 9 year old? I had to duck that one. Actually there were a lot of buttons for which I had to say "let's talk about that another time". Even so, there were plenty of buttons he could understand and play with right away (memory, powers, roots, etc). I couldn't get over how excited he was by this calculator, more than any toy in recent memory. Plus it led to discussions about math that he hadn't learned yet. I explained factorial to him, and he then proceeded to find the biggest factorial the calculator could compute (that's probably what every math geek does with their first scientific calculator). We talked about logarithms, scientific notation, permutations and combinations. Later in the week he as asking about averages so we explored statistics and mean.

It was a lot of fun exploring these things with him. One of the best things about raising kids is that you get to re-experience things that you've taken for granted for so many years. It also led to me reflecting on the various calculators I have owned over the years. I'm sort of a sucker for a new calculator so I've owned a lot more than really were necessary. I owned a few TI calculators before being bitten by the HP bug in 1983, when I bought an HP-15C . Of course I coveted an HP-41 at the time, but it was way outside my budget.

High quality tools make a job more enjoyable (or less frustrating depending on the work). The best tools are the ones that fit you perfectly. This holds for a hammer, reciprocating saw, laptop computer, text editor, or calculator. If I cooked a lot I'd probably feel the same way about cheese graters and frying pans. In "Zen and the Art of Motorcycle Maintenance", Robert M. Pirsig writes about "gumption traps". For me, a mediocre tool is a major gumption trap, so I really like my tools to be good ones. The HP-15C was just such a tool, and served me well through many classes in high school and college.

After the HP-15C I went through a number of other calculators, tempted by the promise of new features and capabilities: HP-28S, HP-42S, HP-48G, HP-49g, HP-49g+. Of those, the HP-42S has remained my favorite. Excellent keyboard, compact, good battery life, really nice base conversion, and pretty much every numerical feature I have ever needed. Unfortunately the keyboard is starting to wear out and misses the occasional key press. Soon I may have to give up my favorite tool. I'm not sure what to replace it with.

Maybe I'll go back to the HP-48G. It is pretty big, a little slow, and the display can be hard to read. But the keyboard is excellent (even better than the HP-42S in my opinion).

The HP-49g+ is an interesting device. So close to being great, but hampered by a poor keyboard. I love the fact that I can completely customize it (like the 48G). The symbolic capabilities are amazing. But the keyboard is weak, the calculator is a little big for my taste, and the paint is flaking. Maybe the newer HP-50g is the answer. From most reports it seems like HP finally has keyboard quality under control again. But after the HP-49g and HP-49g+ I'm a little wary.

The HP-35s is another option, but it feels like a step down from the HP-42s.

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