Data retention - lifetime prediction of modern calculators

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I have a Casio Data-Cal DC850 for more than 10 years, or 20 maybe. Even it is a credit card size calculator it supports dual coin battery for data retention. The quality is so good it is still working perfectly today. Every key is functioning, and the LCD screen is perfect.

I'd say the engineers of this product did an excellent job for both design and manufacturing quality.

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