Introduction: Build Your Calculator Using Arduino!

About: I'm a high school senior who is very interested in coding, robotics, drawing, dancing, video making, and photography.

Hey guys! Want to learn how to use a serial monitor input and output. Well here you've got the perfect tutorial on how to do so! In this instructable, I will guide you through the simple steps needed to create a calculator using the Arduino serial monitor.

Step 1: Downloading the Arduino IDE

Download and Install the Arduino IDE (Interactive Development Environment) using the link below: Choose and save the version that best suits your operating system and configuration.

Step 2: Hardware Materials

  1. 1 Arduino board
  2. 1 cable to connect Arduino board to your computer

Step 3: Building the Hardware

1) Connect Arduino to your computer

Step 4: Downloading and Running the Program

Download the attached arduino program to your laptop. Connect the arduino to your laptop, and run the program.

In the arduino IDE, Open Tools->serial monitor. Type in a calculation to be made, for example, 3+2, and you will get the result as 5. You can also try subtraction, multiplication and division as follows:

4+2 (you will get Result = 6)

8-3 (you will get Result = 5)

5*3 (you will get Result = 15)

10/2 (you will get Result = 5)

Step 5: Understanding the Program

First let's understand how serial port input and output works. A user can enter data in the input field in the serial monitor window to send values and data to the Arduino. Any serial program, or even a custom serial application can be used to send data to the Arduino instead of using the Serial Monitor window.Similarly the user can output data to serial monitor.

We are now going to use this for building our own calculator.

First in setup() method:

We initiatilize variables and the serial port.

Serial.begin(9600); // begins serial communications

Serial.println("Send me a calculation");

Serial.println("For example: 2+3");

Then in loop() method:

while(Serial.available() > 0) { // while there is data being sent to arduino,

number1 = Serial.parseInt();

operation =; // operation will be the first char after the first number

number2 = Serial.parseInt(); // stores the second number in number2

Then we call calculate() and print the result of the calculation.

calculate() is the custom function that performs the calculations. Lets understand how that works.

If (operation == '+'), it adds the two numbers and stores the result in "result" variable.

If (operation == '-'), it subtracts the two numbers and stores the result in "result" variable.

If (operation == '*'), it multiplies the two numbers and stores the result in "result" variable.

If (operation == '/'), it divides the two numbers and stores the result in "result" variable.

Otherwise, it prints "Error"