Scientific calculator

Calculator replaced manual (mechanical) computing devices and appliances, such as abaca, abacus, mathematical tables (first of all - a table of logarithms), slide rules, mechanical or electro-mechanical calculating machines.
Depending on the capabilities of the target and scope of the calculators are divided into elementary, accounting, engineering (scientific), financial. The individual classes are usually emit programmable calculators that provide the ability to perform complex calculations on prepacked program, as well as graphics - supporting the construction and display graphics. Specialized calculators are designed to perform calculations in a fairly narrow area; these calculators are now increasingly being implemented in the form of programs for generic PCs, PDAs, tablets, although they can be made and "iron".

In the execution of engineering calculators can be desktop or compact (pocket). Some models have interfaces for connecting a personal computer, a printing apparatus, an external memory or other external devices. There are calculators built into personal computers, cell phones, PDAs and even watches. Specialized engineering calculators built in appliances (such as a simple medical calculator can be integrated into a sports trainer).

The keyboard includes a scientific calculator keys (buttons), pressing which provides input numbers and perform operations and functions. The keyboard includes at least the following keys:

Digital - ten keys with Arabic numerals from 0 to 9 to input numbers. It is also possible to use complex commands. Traditionally keys 1-9 are located square 3x3, unit - the bottom left, nine - right at the top, zero - separately under the unit (the same location, that additional right field digital computer keyboard).
The decimal point (dot) - to enter the decimal point.
Arithmetic operations - to enter "+" operations (addition), "-" (subtraction), (multiplication), (division) "?" "?".
In addition to these required keys may include a scientific calculator (and usually contains) a greater or smaller number of keys computing functions with memory registers, control calculation procedure. Pressing these keys leads to the implementation of the operations or the calculation function, indicated on it, from the number displayed on the calculator display. Composition of supported functions is determined by the calculator model. Calculators with algebraic calculation logic are also key staples.