This is a simple calculator with basic mathematical operations. You can download full source code of this project from Github https://github.com/arunkfedex/SimpleCalculator We are using ViewModel and LiveData so we need to add those dependencies in build.gradle file. build.gradle plugins { id 'com.android.application' id 'kotlin-android' } android { compileSdk 30 defaultConfig { applicationId "com.arun.androidtutsforu.simplecalculator" minSdk 21 targetSdk 30 versionCode 1 versionName "1.0" testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro' } } compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 ta