Calculator

What is the Invention?
An electronic calculator is a small, portable, often inexpensive electronic device used to perform both basic and complex operations of arithmetic. Modern calculators are more portable than most computers.
Modern electronic calculators vary from cheap, give-away, credit-card sized models to sturdy desktop models with built-in printers. They became popular in the mid-1970s as integrated circuits made their size and cost small. By the end of that decade, calculator prices had reduced to a point where a basic calculator was affordable to most and they became common in schools.
In addition to general purpose calculators, there are those designed for specific markets; for example, there are scientific calculators which include trigonometric and statistical calculations. Some calculators even have the ability to do computer algebra.
In 1986, calculators still represented an estimated 41% of the world's general-purpose hardware capacity to compute information. This diminished to less than 0.05% by 2007.
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.
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...