Angularjs Data Binding Not Updating in Controller
<p>there is a problem that I couldn't understand. 
I copied my code below. 
The problem is when I clicked on a number it must update $scope.screen.operation but it is not updating it. Do I know data binding in a wrong way ?</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>(function() {
    var app = angular.module('electronApp', []);

    app.controller('MainCtrl', function ($scope) {

        $scope.numbers = {
            one: '',
            two: ''
        };

        $scope.operation = '';

        $scope.screen = {
            operation: $scope.numbers.one +' '+ $scope.operation +' '+ $scope.numbers.two,
            result: ''
        };

        $scope.number = function (number) {

            if($scope.operation == '') {
                $scope.numbers.one = '' + $scope.numbers.one + number;
            }

            console.log($scope.screen.operation);

        }

    });
})();</code></pre>
<pre class="snippet-code-css lang-css prettyprint-override"><code>.screen{
    border: 1px solid #bbb;
    background-color: #fafafa;
    border-radius: 2px;
    height: 200px;
    margin-top: 15px;
    padding: 15px;
    position: relative;
}
.screen .operation-list{
    font-size: 16px;
    font-weight: bold;
}
.screen .result{
    font-size: 24px;
    font-weight: bold;
    position: absolute;
    right: 15px;
    bottom: 15px;
    left: 15px;
    text-align: right;
}

.button-box{
    margin-top: 5px;
}
.button-box .row div{
    padding: 5px 5px;
}
.button-box .row div:first-child{
    padding-left: 0;
}
.button-box .row div:last-child{
    padding-right: 0;
}
.button-box .row div button{
    width: 100%;
    height: 40px;
    font-size: 16px;
    font-weight: bold;
    padding: 0;
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
&lt;html ng-app="electronApp"&gt;
  &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;title&gt;Hello World!&lt;/title&gt;
 
 &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" /&gt;

    &lt;script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.8/angular.min.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
 &lt;div class="container-fluid" ng-controller="MainCtrl"&gt;
      &lt;div class="screen col-xs-12"&gt;
          &lt;div class="operation-list" ng-bind="screen.operation"&gt;&lt;/div&gt;
          &lt;div class="result"&gt;
              &lt;span&gt;{{screen.result}}&lt;/span&gt;
          &lt;/div&gt;
      &lt;/div&gt;
      &lt;div class="col-xs-12 button-box"&gt;
          &lt;div class="row"&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(1)"&gt;1&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(2)"&gt;2&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(3)"&gt;3&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="operation"&gt;+&lt;/button&gt;&lt;/div&gt;
          &lt;/div&gt;
          &lt;div class="row"&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(4)"&gt;4&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(5)"&gt;5&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(6)"&gt;6&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="operation"&gt;-&lt;/button&gt;&lt;/div&gt;
          &lt;/div&gt;
          &lt;div class="row"&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(7)"&gt;7&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(8)"&gt;8&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(9)"&gt;9&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="operation"&gt;*&lt;/button&gt;&lt;/div&gt;
          &lt;/div&gt;
          &lt;div class="row"&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="number" ng-click="number(0)"&gt;0&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="clear"&gt;Tmzl&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="backspace"&gt;Sil&lt;/button&gt;&lt;/div&gt;
              &lt;div class="col-xs-3"&gt;&lt;button class="btn btn-default" button-type="operation"&gt;/&lt;/button&gt;&lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
 &lt;/div&gt;
 
  &lt;/body&gt;

&lt;/html&gt;</code></pre>
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</div>
</p>