Factorial

angular.module('mainApp', [])
  .controller('MainCtrl', function($scope) {
  })
  
  .filter('factorial', function() {
    return    function factorial(n) {
      return n === 0 ? 1 : n * factorial(n - 1);
    }

  });

<!DOCTYPE html>
<html ng-app="mainApp">

<head>
  <meta charset="utf-8" />
  <title>AngularJS Factorial Plunker</title>
  <script>
    document.write('<base href="' + document.location + '" />');
  </script>
  <link rel="stylesheet" href="style.css" />
  <script data-require="angular.js@1.4.x" src="https://code.angularjs.org/1.4.9/angular.js" data-semver="1.4.9"></script>
  <script src="app.js"></script>
</head>

<body ng-controller="MainCtrl">
  <label for="fact">Your value</label>
  <input id="fact" ng-model="Value" ng-init="Value=0" /> as a factorial {{Value | factorial}}
</body>

</html>

/* Put your css in here */