The Casio 14-A was indeed the world’s first all-electric desk calculator. But by “desk calculator,” they literally mean “a desk that is a calculator.” The display/keyboard pictured was literally attached to a desk filled with hundreds of relays and weighed 140 kg. [0]
The “all-electric” claim is interesting. There had been scores of electric calculators for decades (Friden, Marchant, etc.) but were merely driven by an electric motor. The calculations were still performed by gears and cams and linkages.
https://ww1.microchip.com/downloads/en/Appnotes/90003250A.pd...
It could be fun to implement a scientific notation result display for answers that would otherwise overflow, although off the top of my head I'm not sure what the cleanest way to do that is.