diff --git a/AndroidCalculator/Base.lproj/Main.storyboard b/AndroidCalculator/Base.lproj/Main.storyboard
index 09f95c7..9089d86 100644
--- a/AndroidCalculator/Base.lproj/Main.storyboard
+++ b/AndroidCalculator/Base.lproj/Main.storyboard
@@ -43,6 +43,9 @@
                                 <state key="normal" title="0">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="fKV-LM-t0P"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="nAR-KS-hdA">
                                 <rect key="frame" x="16" y="469" width="80" height="80"/>
@@ -51,6 +54,9 @@
                                 <state key="normal" title="1">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="3tS-Vs-uwN"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="kDf-qC-jcV">
                                 <rect key="frame" x="104" y="469" width="80" height="80"/>
@@ -59,6 +65,9 @@
                                 <state key="normal" title="2">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="7dd-g7-d1V"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="JA3-GM-FCC">
                                 <rect key="frame" x="192" y="469" width="80" height="80"/>
@@ -67,6 +76,9 @@
                                 <state key="normal" title="3">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="SQe-6n-LS3"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="lNe-oW-jh1">
                                 <rect key="frame" x="16" y="381" width="80" height="80"/>
@@ -75,6 +87,9 @@
                                 <state key="normal" title="4">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="YHI-GM-GHt"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="K0o-vl-kE7">
                                 <rect key="frame" x="104" y="381" width="80" height="80"/>
@@ -83,6 +98,9 @@
                                 <state key="normal" title="5">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="fTX-1h-ZFC"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="1p3-kG-6iM">
                                 <rect key="frame" x="192" y="381" width="80" height="80"/>
@@ -91,6 +109,9 @@
                                 <state key="normal" title="6">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="dK6-yT-RSF"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="wGn-JZ-stq">
                                 <rect key="frame" x="16" y="293" width="80" height="80"/>
@@ -99,6 +120,9 @@
                                 <state key="normal" title="7">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="8jc-pf-wxa"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="XMC-8P-7aZ">
                                 <rect key="frame" x="104" y="293" width="80" height="80"/>
@@ -107,6 +131,9 @@
                                 <state key="normal" title="8">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="X0L-rt-8nz"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="ePk-jK-elJ">
                                 <rect key="frame" x="192" y="293" width="80" height="80"/>
@@ -115,6 +142,9 @@
                                 <state key="normal" title="9">
                                     <color key="titleColor" cocoaTouchSystemColor="darkTextColor"/>
                                 </state>
+                                <connections>
+                                    <action selector="clickNumberButton:" destination="BYZ-38-t0r" eventType="touchUpInside" id="5kj-8D-26R"/>
+                                </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="K66-JV-tKt">
                                 <rect key="frame" x="16" y="205" width="80" height="80"/>
@@ -175,6 +205,16 @@
                     </view>
                     <connections>
                         <outlet property="borderView" destination="srp-dc-mcA" id="ETm-Yj-q7C"/>
+                        <outletCollection property="numberButtons" destination="iKJ-gm-pgJ" collectionClass="NSMutableArray" id="pku-qD-GzX"/>
+                        <outletCollection property="numberButtons" destination="nAR-KS-hdA" collectionClass="NSMutableArray" id="BPw-Wl-WA0"/>
+                        <outletCollection property="numberButtons" destination="kDf-qC-jcV" collectionClass="NSMutableArray" id="DW5-pD-IzB"/>
+                        <outletCollection property="numberButtons" destination="JA3-GM-FCC" collectionClass="NSMutableArray" id="E5h-iZ-xb4"/>
+                        <outletCollection property="numberButtons" destination="lNe-oW-jh1" collectionClass="NSMutableArray" id="Jl8-WL-0a1"/>
+                        <outletCollection property="numberButtons" destination="K0o-vl-kE7" collectionClass="NSMutableArray" id="UdG-7i-Yhk"/>
+                        <outletCollection property="numberButtons" destination="1p3-kG-6iM" collectionClass="NSMutableArray" id="Adm-Y9-ZcM"/>
+                        <outletCollection property="numberButtons" destination="wGn-JZ-stq" collectionClass="NSMutableArray" id="bA3-Bd-Lw7"/>
+                        <outletCollection property="numberButtons" destination="XMC-8P-7aZ" collectionClass="NSMutableArray" id="qd2-ue-ceg"/>
+                        <outletCollection property="numberButtons" destination="ePk-jK-elJ" collectionClass="NSMutableArray" id="zOR-Ye-CD7"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
diff --git a/AndroidCalculator/ViewController.swift b/AndroidCalculator/ViewController.swift
index 82c550e..6e7550a 100644
--- a/AndroidCalculator/ViewController.swift
+++ b/AndroidCalculator/ViewController.swift
@@ -11,6 +11,11 @@ import UIKit
 class ViewController: UIViewController {
 
   @IBOutlet weak var borderView: UIView!
+  @IBOutlet var numberButtons: [UIButton]!
+  
+  @IBAction func clickNumberButton(_ sender: UIButton) {
+    print(numberButtons.firstIndex(of: sender)!)
+  }
   
   override func viewDidLoad() {
     super.viewDidLoad()