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Nowadays many people have a calculator with them as part of their mobile phone and/or personal digital assistant. Engineers and accountants make use of calculators for problems where a computation is not complex enough to demand the use of a general-purpose computer. Students use calculators for schoolwork. Also, some wrist watches contain a calculator (although this was more a fad of the 1980s).
Today calculators are electronic, and are made by numerous manufacturers, in countless shapes and sizes varying from cheap, give-away, credit-card sized models to more sturdy adding machine-like models with built-in printers. Only a very few companies develop and make modern professional engineering and finance calculators; the most well-known are Casio, Hewlett-Packard (HI)and Texas Instruments (TI). Such calculators are good examples of embedded systems.
In the past, mechanical and clerical aids such as abaci, comptometerA Comptometer is a type of mechanical (or electro-mechanical) adding machine. The comptometer was the first adding device to be driven solely by the action of pressing keys, which are arranged in an array of vertical and horizontal colums. Comptometer is,s, Napier's bonesThis article started off as a machine translation of an article from the Spanish Wikipedia. It needs lots of revision and editing before it is usable here. This is a work in progress. Napier's bones are an abacus invented by John Napier for calculation of, books of mathematical tableBefore calculators were cheap and plentiful, people would use mathematical tables —lists of numbers showing the results of calculation with varying variables— to simplify and drastically speed up computation. Most common are tables of multiplication, whics, slide ruleThe slide rule is a portable, mechanical, analog computer usually consisting of three interlocking calibrated strips and a sliding cursor used to record intermediate results. It was once widely used for rapid, approximate scientific and engineering calculs, adding machineAn adding machine is a type of calculator. Usually this sort of calculator is specialized for bookkeeping calculations. In the United States, very old adding machines were usually (always?) built to read in dollars and cents. They required the user to puls, were used for serious numeric work, and the word "calculator" denoted a person (most often female) who did such work for a living using such aids as well as pen and paperPaper is a thin, flat material produced by the compression of fibres. The fibers used are usually natural and based upon cellulose. The most common material is wood pulp from pulpwood (largely softwood) trees such as pines, but other vegetable fiber mater. This semi-manual process of calculation was tedious and error-prone.
Today most calculators are handheld microelectronic devices, but in the past some calculators were as large as today's computers. The first mechanical calculatorA mechanical calculator is a device that does computations without the aid of electricity. Such devices include: Abaci Napier's bones Curta Charles Babbage's Analytical engine Mathematical tools.s were mechanical desktop devices, which were soon replaced by electromechanical desktop calculators, and then by electronic devices using first thermionic valves, then transistors, then hard-wired integrated circuit logic.
A pocket calculator is a small battery-powered or solar powered electronic digital computer made possible by integrated circuit and semiconductor technology. Typically they are limited to an 8–10 digit single-number display and a few basic functions of arithmetic, but some modern ones have more of the features of a general-purpose computer. Pocket calculators rendered the slide rule obsolete.
Calculators vary in their capabilities. Some are limited to only basic arithmetic; others support trigonometric and other mathematical functions. The most advanced modern calculators are programmable, can display graphics, and include features of computer algebra systems.