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I have continued my experiments with drowned calculators. That first sacrifice has been submerged three separate times in warm saltwater, and after a few hours it always comes back to life in good working order. I do think that its solar power system has been degraded somewhat. It seems to need somewhat brighter light to become active. 

The "Casio fx260 solar" in the year 2015 is not the same calculator that was sold under this model name in 2005. The current model is slightly larger overall (about 3% in width and height), has a considerably larger display, a more sensitive solar cell, and a capacitive power backup that will last for about thirty seconds if the lights go out. I realized that I should drown the new model just to be sure that the modifications have not made it more sensitive to water. When I tossed one of the newer calculators in saltwater, I was amazed to discover that I could still work calculations on it while it was submerged in an inch of water. The gaps that allow water in, even around the keys, are small, and it takes a while to get even a small amount of water inside the case. By shaking the calculator underwater, I was eventually able to get it to flood and shut down. Even more so than the model from ten years ago, this calculator does not want to sink. It floats well. So I put a weight in top of it and left it in the water for fifteen minutes...

After rescuing it from the briny deep, the calculator was still alive. I could work calculations on it, sort of, less than a minute after pulling it from the water and giving it a good shake. However, the display was somewhat garbled. When I entered 45 and hit the sine key, I could see that it was displaying the correct 0.70710678, but if I had not known the number, I really would not have been able to read it. So I shook it out some more, toweled it down, and left it out to dry. After four hours, everything was back to normal. No problems at all.

I'm now convinced that my initial test was not a fluke or a lucky accident. These calculators are seaworthy. Naturally the smart practice would be to put the calculator inside a transparent zip-lock bag (a sandwich bag) and work the keys through the plastic rather than letting it get wet at all. That's a simple precaution. The point here is that this is a genuinely robust device. I understand why some people worry about more sophisticated, complex electronic devices like smartphones, iPads, and laptops. They're sensitive. But calculators are nothing to worry about, especially one like the fx260 that's solar-powered and cheap, too.

Frank Reed
ReedNavigation.com