Design
Modern electronic calculators contain a keyboard with buttons for digits and arithmetical operations. Some even contain 00 and 000 buttons to make large numbers easier to enter. Most basic calculators assign only one digit or operation on each button. However, in more specific calculators, a button can perform multi-function working with key combination or current reckoning mode.
Calculators usually have liquid crystal displays as output in place of historical vacuum fluorescent displays. See more details in technical improvements. Fractions such as 1⁄3 are displayed as decimal approximations, for example rounded to 0.33333333. Also, some fractions such as 1⁄7 which is 0.14285714285714 (to 14 significant figures) can be difficult to recognize in decimal form; as a result, many scientific calculators are able to work in vulgar fractions or mixed numbers.
Calculators also have the ability to store numbers into memory. Basic types of these store only one number at a time. More specific types are able to store many numbers represented in variables. The variables can also be used for constructing formulae. Some models have the ability to extend memory capacity to store more numbers; the extended address is referred to as an array index.
Power sources of calculators are batteries, solar cells or electricity (for old models) turning on with a switch or button. Some models even have no turn-off button but they provide some way to put off, for example, leaving no operation for a moment, covering solar cell exposure, or closing their lid. Crank-powered calculators were also common in the early computer era.
Read more about this topic: Calculator
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—Henry David Thoreau (1817–1862)
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