NavList:

Bob Goethe, you wrote:
"I see that the Canon F605G calculator has a <° ' "> button on it.  It is available at a drugstore near my house for $20 Canadian.  I think that means if you were paying in US dollars you could get it for a wink and a smile."

The Casio fx-260 solar (and the newer II version) which I recommend and use in some classes has a similar capability. As it happens, I never teach students to use that key. It's much better to know how to work the calculation directly. Some of them learn to use that key later. You can download my functionally-identical app for Android at the page for my Modern Celestial Navigation class. My app version looks and feels like the original calculator, complete with visual key press and LCD-style numerical display. It's for teaching --not intended as a substitute for an actual calculator!

The Casio fx-260 solar is widely available at office supply stores and also at Walmart. Locally, the retail price is usually around $8.50 to $9.50 (USD). On Canadian amazon.ca, the price seem to be CDN$16 or higher.

These calculators are described as "solar-powered" but will function in very low light. I've done trig calculations powered by candlelight --admittedly with the calculator close enough to the flame to risk melting it, but still. These calculators are also significantly water-resistant. They recover from dunking in warm saltwater. In fact, they float for a rather long time, and before water gets inside, you can even run up a spherical triangle while the calculator is underwater! Don't try this with my Android app. :)

In case I haven't mentioned this recently, the calculator's keypad has a little logical puzzle for you. It's solar-powered... but it has an "ON" key.

Frank Reed
PS: I have not tried spherical trigonometry with the calculator underwater and illuminated only by candlelight. I suspect that would not work!