The best calculator?

Opinions vary, especially when it comes to calculators. Especially calculators. You can roughly divide humanity, in that respect, in three camps: the righteous HP fans, the TI heretics, and the “I don’t care” pagans. Really? What is there to argue about a calculator? Who cares?

There once was a time where numbers mattered. For most of us that time was high school, and for some of us it was even college. Once you’re working as a professional you quickly discover that real life math is a lot easier than what was taught in college, there’s just a lot more of it. Enter Excel, and we rarely ever need a calculator again. And when we do, well there’s a calculator app on our smartphone, after all.

But the smartphone is small, and there’s no substitute for feedback of real buttons. And then there’s the annoying fact that nearly all modern calculators (real or app-ones) use algebraic entry modes.

Enter the trusted, 1980s vintage Hewlett-Packard 15C. The pinnacle of pocket calculators? The HP 42S was perhaps more advanced and had, in my eyes, a better button layout, but it is very hard to beat the 15C in elegance, size, and attitude.

An American made Hewlett-Packard 15C (made in the first week of 1987)

An American made Hewlett-Packard 15C (made in the first week of 1987)

What is it that I like about this calculator? First of all, the display. Good ole’ LCD segments, instead of dots; much easier on the eyes. Second of all, this is a USA-made calculator in a time when it meant something. It feels about three times as heavy as a modern day, similar sized calculator. Third of all, the horizontal layout may look weird, but it is actually easier to hold than modern-day vertically laid out calculators. And finally, it uses RPN. If you’re unfamiliar with that… You’re forgiven. But once you’ve used an RPN calculator you will never want to go back. What is RPN? I’ll save that for a separate blog post.

A few nice touches on this calculator; first of all, the backside contains a “cheat sheet” with often used unit conversions, used conventions for complex numbers (yes, the HP15C can natively calculate with complex numbers) and a diagram on how to insert the batteries (three SR44 button cells that can power the calculator for years).

The electronics are wrapped inside a sheet with three layers. The middle layer is conductive to protect the electronic against electrostatic charges; the outsides are non-conductive to protect against short-circuiting. The result is a dust resistant solid calculator that is said to be able to survive the electro-magnetic pulse of a nuclear explosion.

Mine was a “mint condition” used calculator that I bought on eBay. The seller did not quite understand the meaning of the word “mint”—the 15C nameplate was missing, and the keys were sticky, but I got it for a very good price so I decided to live with it. The sticky keys were resolved by soaking the calculator in distilled water for a day, and then squeezing a paperclip underneath the keys to remove the gunk. Let it sit for a few days and remove the last moisture with a 15 minute stay in the oven. Yes, these are calculators that laugh at such treatments! It works as new now.


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