The man who the first time found or created the calculator is William Seward Burroughs. Born 1857 Rochester, N.Y - Died 1898. In 1885, Burroughs filed his first patent for a calculating machine. However, his 1892 patent was for an improved calculating machine with an added printer. William Seward Burroughs invented the first practical adding and listing machine - National Inventors Hall of Fame.
In the past, mechanical clerical aids such as abaci, comptometers, Napier's bones, books of mathematical tables, slide rules, or mechanical adding machines were used for numeric work. This semi-manual process of calculation was tedious and error-prone.
Modern calculators are electrically powered (usually by battery and/or solar cell) and vary from cheap, give-away, credit-card sized models to sturdy adding machine-like models with built-in printers. They first became popular in the late 1960s as decreasing size and cost of electronics made possible devices for calculations, avoiding the use of scarce and expensive computer resources. By the 1980s, calculator prices had reduced to a point where a basic calculator was affordable to most. By the 1990s they had become common in math classes in schools, with the idea that students could be freed from basic calculations and focus on the concepts.
Computer operating systems as far back as early Unix have included interactive calculator programs such as dc and hoc, and calculator functions are included in almost all PDA-type devices (save a few dedicated address book and dictionary devices).
Most calculators contain the following buttons: 1,2,3,4,5,6,7,8,9,0,+,-,×,÷ (/),.,=,%, and ± (+/-). Some even contain 00 and 000 buttons to make larger calculations easier to compute.
Source : http://en.wikipedia.org/wiki/Calculator
Source : http://en.wikipedia.org/wiki/Calculator
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