Description

Calculator replaced manual(mechanical)computing devices and appliances, such as abaca,abacus,mathematical tables (first of all - a table of logarithms),sliderules, mechanical or electro-mechanical calculatingmachines.
Depending on the capabilities of the target and scope ofthecalculators are divided into elementary, accounting,engineering(scientific), financial. The individual classes areusually emitprogrammable calculators that provide the ability toperformcomplex calculations on prepacked program, as well asgraphics -supporting the construction and display graphics.Specializedcalculators are designed to perform calculations in afairly narrowarea; these calculators are now increasingly beingimplemented inthe form of programs for generic PCs, PDAs, tablets,although theycan be made and "iron".

In the execution of engineering calculators can be desktoporcompact (pocket). Some models have interfaces for connectingapersonal computer, a printing apparatus, an external memoryorother external devices. There are calculators built intopersonalcomputers, cell phones, PDAs and even watches.Specializedengineering calculators built in appliances (such as asimplemedical calculator can be integrated into a sportstrainer).

The keyboard includes a scientific calculator keys(buttons),pressing which provides input numbers and performoperations andfunctions. The keyboard includes at least thefollowing keys:

Digital - ten keys with Arabic numerals from 0 to 9 toinputnumbers. It is also possible to use complex commands.Traditionallykeys 1-9 are located square 3x3, unit - the bottomleft, nine -right at the top, zero - separately under the unit (thesamelocation, that additional right field digitalcomputerkeyboard).
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 ascientificcalculator (and usually contains) a greater or smallernumber ofkeys computing functions with memory registers, controlcalculationprocedure. Pressing these keys leads to theimplementation of theoperations or the calculation function,indicated on it, from thenumber displayed on the calculatordisplay. Composition ofsupported functions is determined by thecalculator model.Calculators with algebraic calculation logic arealso keystaples.