In order to use this application you need to have JDK 15 installed on your PC. If you have not installed it before, click on this link : https://www.oracle.com/in/java/technologies/javase-jdk15-downloads.html and then install required version of JDK 15.0.2 for your OS. After this, download "Calculator.jar" and open this file to run the application. For developers, I have added few files "Calculator.java", "Display.java" and "Display.form". The first two files contain source code and the last one has the main GUI.