# How calculator works, Schematic Circuit Diagram

Before start making an adding calculator you need to have some basic knowledge of binary adder how to add the binary digit. As we know we use decimal number system in our daily life because of we have 10 fingers, and 10 fingers make us easy to calculate numbers, but not easy if the number is large. So someone has discovered a calculator. But calculator does not have any fingers it has only a power source (ie battery ) and by using that energy it can calculate the large number, using its two states 1 or 0. that is power is available (1) and power is not available (0). By adding some extra circuitry the binary number seems to be like a decimal number but actually, it is just a combination of LEDs that make it digits.

In this section, we are actually making a binary calculator that can add up to 4 digits (ie 4 bit) .we need some integrated circuit to observe the result of a binary calculator in the decimal number system. So we have used 4511 integrated circuit ic to decode the result of the binary adder and that is sent to seven segment display .so the component required is

- AND gate ic
- OR gate ic
- XOR gate ic
- 4511 binary to hex decoder
- Seven segment display
- A power source and some resistors

In this section we only discuss binary calculator, if you want to learn about how seven segment works and how binary to hex decoder ic works please click the highlighted area.

**HALF ADDER**

A half adder is a combination of the digital circuit that can add numbers but cannot add the carry . in half adder all calculation is based without carrying. here is the circuit diagram of the half adder

the circuit diagram of half adder is as shown in the figure below

to understand the result of the half adder circuit you need to understand the basis of the truth table of the basic logic gates circuit please refer to this section for more about the gates

##### full adder

the block diagram of full adder circuit is given below

**Schematic Diagram:**

this is full adder circuit using XOR, OR and AND gate ic. The output is changing according to the input if we combine then-number of half adder it will able to add n bit binary digits as shown in the figure below