Kotlin Program to Make a Simple Calculator Using When

Kotlin, a versatile and concise programming language, allows developers to achieve just that. In this post, you’ll learn to Kotlin Program to Make a Simple Calculator Using When.

This tutorial is designed for beginners and intermediate developers looking to enhance their Kotlin skills while building a practical application. So, let’s dive into the world of Kotlin and create a user-friendly calculator.

Example: Kotlin Program to Make a Simple Calculator Using When

import java.util.Scanner

fun main(){

   val input = Scanner(System.`in`)

    print("Enter first Number: ")
    val firstNumber = input.nextInt()

    print("Enter second Number: ")
    val secondNumber = input.nextInt()

    print("Enter Action (+, -, *, /, %): ")
    val choice  = input.next()[0]

    val result  = when(choice){
        '+' -> firstNumber  + secondNumber
        '-' -> firstNumber  - secondNumber
        '*' -> firstNumber  * secondNumber
        '/' -> firstNumber  / secondNumber
        '%' -> firstNumber  % secondNumber
        else -> {
            System.err.println("Not a valid operation")


In this tutorial, we’ve explored how to create a simple calculator using Kotlin’s when expression. We’ve covered the basics of Kotlin, set up our development environment, designed a user-friendly interface, implemented calculator logic, and added user-friendly features. You’re now equipped with the knowledge to build your own Kotlin-based applications.

Start experimenting with Kotlin, explore more advanced features, and create even more exciting projects!


  1. Is Kotlin suitable for Android app development?Yes, Kotlin is an excellent choice for Android app development. It offers concise syntax, null safety, and full interoperability with Java.
  2. Can I use Kotlin for web development?Yes, Kotlin can be used for web development as well. It can be compiled to JavaScript, making it a versatile choice for both frontend and backend development.
  3. What is the advantage of using the when expression in Kotlin? The when expression in Kotlin allows you to handle multiple conditions cleanly and concisely. It’s particularly useful for scenarios like our calculator where different actions need to be taken based on user input.
  4. Is Kotlin a beginner-friendly language? Kotlin’s concise syntax and modern features make it relatively beginner-friendly. If you have prior programming experience, you should be able to pick it up quickly.
  5. Where can I find more Kotlin resources and tutorials? You can find a wealth of Kotlin resources, tutorials, and documentation on the official Kotlin website and various online programming communities.
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