Calculator

A calculator is a device for performing mathematical calculations, distinguished from a computer by having a limited problem solving ability and an interface optimized for interactive calculation rather than programming. Calculators can be hardware or software, and mechanical or electronic, and are often built into devices such as PDAs or mobile phones. Modern electronic calculators are generally small, digital, (often pocket-sized) and usually inexpensive. In addition to general purpose calculators, there are those designed for specific markets.

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.

Calculator is a basic calculator application made by Apple and bundled with Mac OS X. It has three modes: basic, scientific, and programmer. Basic includes a number pad, buttons for adding, subtracting, multiplying, and dividing, as well as memory keys. Scientific mode supports exponents and trigonometric functions, and programmer mode gives the user access to more options related to computer programming. The Calculator program has a long history going back to the very beginning of the Macintosh platform, where a simple four-function calculator program was a standard desk accessory from the earliest system versions.

A calculating machine is a machine designed to come up with calculations or, in other words, computations. One noted machine was the Victorian British scientist Charles Babbage's Difference Engine (No. 2), designed in the 1840s but never completed in the inventor's lifetime. A working example, based on Babbage's original specifications and using only materials available during the mid-19th century, was built at the London Science Museum in the late 1990s.