Calculator watch Calculator watch A calculator watch is a digital watch with a built in calculator, usually including buttons on the watch face. Calculator watches were first introduced in the 1970s and continue to be produced, despite falling from their peak popularity during the 1980s. The most notable brand is the Casio Databank series, though watches made by Timex were also popular. Most calculator watches contain only a few number of functions such as +, -, x, / and percents. However, there are several models with additional functions: scientific, including transcendent and trigonometry, in models Casio CFX-200, CFX-400, Citizen 49-9421, and also
Solar-powered calculator in modern TI calculators is denoted by a lower case "a" at the end of the model number (e.g. TI-30a). In older models, such as the TI-36 Solar, "Anylite Solar" is printed on the calculator. As of the 2010s, some very cheap calculators include a "dummy" solar panel, implying that they are solar-powered, when they are actually powered only by battery. Solar-powered calculator Solar-powered calculators are hand-held electronic calculators powered by solar cells mounted on the device. They were introduced at the end of the 1970s. Amorphous silicon has been used as a photovoltaic solar cell material for devices which