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JavaScript
HTML
CSS
Result

angular.module('app', []); 

angular.module('app').controller('CalcController', function($scope, CalcService) {
            $scope.square = function() {
               $scope.result = CalcService.square($scope.number);
            };
         });


angular.module('app').service('CalcService', function(){
            this.square = function(a) {
               return a * a;
            };
         });

  <body  ng-app="app">
    
     <div ng-app = "mainApp" ng-controller = "CalcController">
         <p>sayı girin: <input type = "number" ng-model = "number" /></p>
         <button ng-click = "square()">kare al</button>
         <p>karesi: {{result}}</p>
      </div>