diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
index 45b5654..88ea3aa 100644
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -1,8 +1,5 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
-    <AndroidXmlCodeStyleSettings>
-      <option name="ARRANGEMENT_SETTINGS_MIGRATED_TO_191" value="true" />
-    </AndroidXmlCodeStyleSettings>
     <JetCodeStyleSettings>
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
diff --git a/app/build.gradle b/app/build.gradle
index 4fe5a3d..0ec4fc7 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -31,4 +31,7 @@ dependencies {
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test.ext:junit:1.1.1'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+
+    implementation project(':calculator')
+
 }
diff --git a/app/src/main/java/com/example/multimodule/MainActivity.kt b/app/src/main/java/com/example/multimodule/MainActivity.kt
index 350a63b..b6fa7e7 100644
--- a/app/src/main/java/com/example/multimodule/MainActivity.kt
+++ b/app/src/main/java/com/example/multimodule/MainActivity.kt
@@ -1,12 +1,29 @@
 package com.example.multimodule
 
-import androidx.appcompat.app.AppCompatActivity
+import android.content.Intent
 import android.os.Bundle
+import android.widget.Button
+import androidx.appcompat.app.AppCompatActivity
+import com.example.calculator.ui.CalculatorActivity
 
 class MainActivity : AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+
+        bindListeners()
+    }
+
+    private fun bindListeners() {
+        findViewById<Button>(R.id.calculator_button).setOnClickListener {
+            startCalculatorActivity()
+        }
+    }
+
+    private fun startCalculatorActivity() {
+        startActivity(
+            Intent(this, CalculatorActivity::class.java)
+        )
     }
 }
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 4fc2444..496d8ef 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -6,13 +6,28 @@
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
-    <TextView
+    <Button
+        android:id="@+id/calculator_button"
+        style="@style/Widget.AppCompat.Button.Colored"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="Hello World!"
+        android:text="@string/go_to_calculator"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/textView2" />
 
+    <TextView
+        android:id="@+id/textView2"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="24dp"
+        android:layout_marginTop="24dp"
+        android:layout_marginEnd="24dp"
+        android:text="@string/tools"
+        android:textSize="24sp"
+        android:textStyle="bold"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index eab8222..6fd79da 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1,3 +1,5 @@
 <resources>
     <string name="app_name">dagger-multimodule-app</string>
+    <string name="go_to_calculator">Calculator</string>
+    <string name="tools">Tools</string>
 </resources>
diff --git a/build.gradle b/build.gradle
index 58efbe3..ee7319b 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,7 +5,7 @@ buildscript {
     repositories {
         google()
         jcenter()
-        
+
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:3.5.3'
@@ -19,7 +19,7 @@ allprojects {
     repositories {
         google()
         jcenter()
-        
+
     }
 }
 
diff --git a/calculator/.gitignore b/calculator/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/calculator/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/calculator/build.gradle b/calculator/build.gradle
new file mode 100644
index 0000000..bab1954
--- /dev/null
+++ b/calculator/build.gradle
@@ -0,0 +1,35 @@
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+android {
+    compileSdkVersion 29
+
+
+    defaultConfig {
+        minSdkVersion 21
+        targetSdkVersion 29
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles 'consumer-rules.pro'
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'androidx.core:core-ktx:1.2.0'
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+}
diff --git a/calculator/consumer-rules.pro b/calculator/consumer-rules.pro
new file mode 100644
index 0000000..e69de29
diff --git a/calculator/proguard-rules.pro b/calculator/proguard-rules.pro
new file mode 100644
index 0000000..f1b4245
--- /dev/null
+++ b/calculator/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
diff --git a/calculator/src/androidTest/java/com/example/calculator/ExampleInstrumentedTest.kt b/calculator/src/androidTest/java/com/example/calculator/ExampleInstrumentedTest.kt
new file mode 100644
index 0000000..8eb5226
--- /dev/null
+++ b/calculator/src/androidTest/java/com/example/calculator/ExampleInstrumentedTest.kt
@@ -0,0 +1,24 @@
+package com.example.calculator
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.example.calculator.test", appContext.packageName)
+    }
+}
diff --git a/calculator/src/main/AndroidManifest.xml b/calculator/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..cf6454a
--- /dev/null
+++ b/calculator/src/main/AndroidManifest.xml
@@ -0,0 +1,12 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.calculator">
+
+    <application>
+        <activity
+            android:theme="@style/Theme.Calculator"
+            android:label="Calculator"
+            android:name=".ui.CalculatorActivity"
+            android:screenOrientation="portrait" />
+    </application>
+
+</manifest>
diff --git a/calculator/src/main/java/com/example/calculator/ui/CalculatorActivity.kt b/calculator/src/main/java/com/example/calculator/ui/CalculatorActivity.kt
new file mode 100644
index 0000000..29228bf
--- /dev/null
+++ b/calculator/src/main/java/com/example/calculator/ui/CalculatorActivity.kt
@@ -0,0 +1,48 @@
+package com.example.calculator.ui
+
+import android.os.Bundle
+import android.widget.Button
+import android.widget.EditText
+import android.widget.TextView
+import androidx.appcompat.app.AppCompatActivity
+import com.example.calculator.R
+import com.example.calculator.usecase.SumUseCase
+
+class CalculatorActivity : AppCompatActivity() {
+
+    lateinit var sumUseCase: SumUseCase
+
+    lateinit var firstNumberEditText: EditText
+    lateinit var secondNumberEditText: EditText
+    lateinit var resultTextView: TextView
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.acitivity_calculator)
+
+        sumUseCase = SumUseCase()
+
+        bindViews()
+        bindListeners()
+    }
+
+    private fun calculateSum() {
+        val firstNumber = firstNumberEditText.text.toString().toInt()
+        val secondNumber = secondNumberEditText.text.toString().toInt()
+        val result = sumUseCase.execute(firstNumber, secondNumber)
+        resultTextView.text = result.toString()
+    }
+
+    private fun bindViews() {
+        firstNumberEditText = findViewById(R.id.first_number_edittext)
+        secondNumberEditText = findViewById(R.id.second_number_edittext)
+        resultTextView = findViewById(R.id.result_textview)
+    }
+
+    private fun bindListeners() {
+        findViewById<Button>(R.id.button_calculate).setOnClickListener {
+            calculateSum()
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/calculator/src/main/java/com/example/calculator/usecase/SumUseCase.kt b/calculator/src/main/java/com/example/calculator/usecase/SumUseCase.kt
new file mode 100644
index 0000000..d0432fe
--- /dev/null
+++ b/calculator/src/main/java/com/example/calculator/usecase/SumUseCase.kt
@@ -0,0 +1,9 @@
+package com.example.calculator.usecase
+
+class SumUseCase {
+
+    fun execute(firstNumber: Int, secondNumber: Int): Int {
+        return firstNumber + secondNumber
+    }
+
+}
\ No newline at end of file
diff --git a/calculator/src/main/res/layout/acitivity_calculator.xml b/calculator/src/main/res/layout/acitivity_calculator.xml
new file mode 100644
index 0000000..d37796a
--- /dev/null
+++ b/calculator/src/main/res/layout/acitivity_calculator.xml
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:orientation="vertical"
+    android:background="@android:color/white">
+
+
+    <EditText
+        android:id="@+id/first_number_edittext"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="20dp"
+        android:layout_marginTop="20dp"
+        android:layout_marginRight="20dp"
+        android:textSize="18sp"
+        android:textColor="@android:color/black"
+        android:ems="10"
+        android:hint="@string/insert_first_number_hint"
+        android:inputType="number" />
+
+    <EditText
+        android:id="@+id/second_number_edittext"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="20dp"
+        android:layout_marginTop="20dp"
+        android:layout_marginRight="20dp"
+        android:textSize="18sp"
+        android:ems="10"
+        android:textColor="@android:color/black"
+        android:hint="@string/insert_second_number_hint"
+        android:inputType="number" />
+
+    <Button
+        android:id="@+id/button_calculate"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_margin="32dp"
+        android:padding="8dp"
+        style="@style/Widget.AppCompat.Button.Colored"
+        android:layout_gravity="center"
+        android:text="@string/calculate" />
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:padding="8dp"
+        android:layout_gravity="center"
+        android:layout_height="wrap_content"
+        android:textStyle="bold"
+        android:text="@string/result" />
+
+    <TextView
+        android:id="@+id/result_textview"
+        android:layout_width="wrap_content"
+        android:padding="8dp"
+        android:textSize="24sp"
+        android:layout_gravity="center"
+        android:layout_height="wrap_content"
+        tools:text="200" />
+
+</LinearLayout>
\ No newline at end of file
diff --git a/calculator/src/main/res/values/colors.xml b/calculator/src/main/res/values/colors.xml
new file mode 100644
index 0000000..69b2233
--- /dev/null
+++ b/calculator/src/main/res/values/colors.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorPrimary">#008577</color>
+    <color name="colorPrimaryDark">#00574B</color>
+    <color name="colorAccent">#D81B60</color>
+</resources>
diff --git a/calculator/src/main/res/values/strings.xml b/calculator/src/main/res/values/strings.xml
new file mode 100644
index 0000000..4dac590
--- /dev/null
+++ b/calculator/src/main/res/values/strings.xml
@@ -0,0 +1,7 @@
+<resources>
+    <string name="app_name">calculator</string>
+    <string name="insert_second_number_hint">Put another number here</string>
+    <string name="insert_first_number_hint">Put a number here</string>
+    <string name="calculate">Calculate sum!</string>
+    <string name="result">Result</string>
+</resources>
diff --git a/calculator/src/main/res/values/styles.xml b/calculator/src/main/res/values/styles.xml
new file mode 100644
index 0000000..3f61817
--- /dev/null
+++ b/calculator/src/main/res/values/styles.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <style name="Theme.Calculator" parent="Theme.AppCompat.Light.DarkActionBar">
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+    </style>
+
+</resources>
\ No newline at end of file
diff --git a/calculator/src/test/java/com/example/calculator/ExampleUnitTest.kt b/calculator/src/test/java/com/example/calculator/ExampleUnitTest.kt
new file mode 100644
index 0000000..73dfbe0
--- /dev/null
+++ b/calculator/src/test/java/com/example/calculator/ExampleUnitTest.kt
@@ -0,0 +1,17 @@
+package com.example.calculator
+
+import org.junit.Test
+
+import org.junit.Assert.*
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}
diff --git a/settings.gradle b/settings.gradle
index 01e7b1f..7bead11 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,2 +1,2 @@
-include ':app'
+include ':app', ':calculator'
 rootProject.name='dagger-multimodule-app'