How does a calculator work?
Solar-powered calculators are no different from regular calculators. The work of a computer doesn’t actually require very much power to do. It may take 100 watts to power your desktop computer to do 4 billion operations per second, but the work of a calculator is usually only a dozen calculations (more for fancy trigonometry functions, but only a few hundred). That takes up a tiny, tiny fraction of a watt, and enough to be powered by even a tiny solar cell. Calculators use off-the-shelf low-power CPUs called “embedded” because they’re put inside other devices (including microwave ovens, clocks, toys, etc.) They work just like any other CPU, using transistors on a microchip, except instead of the billions of transistors you’ll get on a computer CPU, you’ll get only a few thousand. The math of how transistors do calculations is beyond the scope of this answer, but I’ll give you a very fast summary: the computer works in binary, with current either flowing or not. The transistor is like a
