Calculators have been in use since the early Renaissance period, but how calculator works is a commonly asked question. Who would have thought to invent such a thing, this long ago? Since then, it has been a handy tool for shopkeepers, accountants, and even scientists for calculations in a quick and easy manner.

**1. What’s the History of Calculator?**

- The very first mechanical calculator was made by
**Wilhelm Schickard**, which was destroyed by fire. - Then, during the mid-17
^{th}century,**Blaise Pascal**, a French mathematician, and physicist invented a mechanical calculator. His father was the supervisor of taxes in Rouen and his work required a lot of arithmetical calculations. So, in order to ease the workload of his father, Blaise designed a machine that could do**4 arithmetical operations**, i.e., addition, subtraction, multiplication, and division. This is how calculator works even today. - Later,
**Arithmometer**was invented in 1820. It was also a mechanic calculator, and its production started in 1851. By this time, people had understood how calculator works and how to use it to reduce their daily work. Hence, it became the first commercially successful calculator. (See Who Invented Math?)

**2. What are the Different Types of Calculators?**

On the basis of purpose, calculators can be of different types, as follows:

**Abacus**– The name comes from the Greek word abax, which means counting fable. It is an ancient calculator having rods and beads fixed vertically/horizontally in a frame. It was**helpful for visually impaired people**when technology was not as advanced.**Scientific Calculators**– These are used in various**mathematics, physics, & trigonometry-related calculations**. These calculators are capable of solving all kinds of scientific calculations.**Basic Calculators**– These have a display of 8-12 digits, and their**keys are numbered from 0 to 9**. They can work on solar power, as well as, battery power and are a perfect choice for basic calculations at home or offices.**Printing Calculators**– These are mostly used by shopkeepers. It**prints the result obtained**from a calculation. These can also work on battery or electricity and are accompanied by a roll of paper which is used in printing the result.**Graphing Calculators**– These have replaced scientific calculators, and can be used to**plot graphs & solve equations**. With the advancement of time, graphing calculators have also started coming in portable sizes.

**3. How Does Calculator Work?**

So, *how calculator works?* Silicon microchips were invented during the late 1960 and early 1970. These microchips enabled the working of the calculators in a simpler manner. The modern calculators **work in the same way as a** **computer** but differ in the type of commands provided. A calculator **needs manual input each time** a user needs to do a calculation, while a computer can be programmed to follow certain functions to carry out the calculations. (Also see Why Does Computer Hardware Fail?)

- The initially pressed number goes to the
**X register**and is stored there. - While the number pressed after entering the function, that is, add or subtract sign, moves to the
**Y register**. - The
**third register**is known as the Flag Register. The functions for the calculations are stored here. ROM or permanent memory is a place in which the functions like square roots, trigonometry operations, etc., are stored. - Finally, pressing the = key causes the calculator to process the contents of both registers as per the sign used and
**display the result**.

**4. What are the Internal Parts of a Calculator?**

The internal parts of any machine are called the** hardware**. These execute the input commands when the keys are pressed.

- A
**processor chip**is like a central processing unit of a computer and carries out all the technical functions of a calculator. They**convert the inputs into signals**and then give the required result on display. The entire phenomenon of how calculator works depends on the processor unit/ chip. - A
**keypad**consists of**numbers**ranging from 0-9 along with**signs**of addition, multiplication, subtraction, division, etc. Modern calculators have signs like square root also. It is a rubber sheet placed above the processor unit in alignment with the sensors of the respective binary units. - A
**power source**can be a**battery or solar cell**through which the calculator generates power to carry out the functions. (See What is 1/4 plus 1/4?)

**5. What are the Various Kinds of Display Panels?**

The output device includes the **Display panel**.

- In a
**basic calculator**, LCD (liquid-crystal displays), VFD (Vacuum fluorescent displays), and LED (light-emitting diode displays) use seven segments that represent each digit of the calculator. - While dot matrix displays are used in
**advanced calculators**.

**6. What are the Different Keys and Their Function?**

The basic calculators have the keys listed below. (See What is a 10-key experience and requirements?)

But, their arrangement and positioning may vary according to the model and sizes of calculators. The said keys are as follows:

- MC/CM- It denotes Memory Clear or Clear Memory.
- MR- Memory Recall.
- M- (Minus) – Memory Subtraction.
- M+ (plus) – Memory Addition.
- C – Clear.
- (+) – Addition.
- (-) – Subtract.
- (/) – Divide.
- (*) – Multiply.
- (.) – Decimal.
- (=) – Equals to or Result.
- (√) – Square root.
- (%) – Percentage.
- CHS (±) – It means to change the sign or toggle the sign.

With the help of hardware and software explanations, it has now become clear how calculator works. (See What is 2/3 + 2/3=?)