var app = angular.module('plunker', []);
        app.controller("MyCtrl", ["$scope", function ($scope) {
            $scope.amount = 0;

            $scope.onSubmit = function () {
                alert("form submitted and Amount is -" + $scope.amount);
            }
        }]);
<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS 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/1.4.12/angular.js" data-semver="1.4.9"></script>
    <script src="app.js"></script>
  </head>

  <body ng-controller="MyCtrl">
        <div>
        <form name="myNumberForm" ng-submit="onSubmit()">
            <input type="number" ng-model="amount" name="amount_field"
                   ng-pattern="/^[0-9]{1,7}$/" required>

            <span ng-show="myNumberForm.amount_field.$error.pattern">Not a valid number!</span>
            <span ng-show="myNumberForm.amount_field.$error.required">This field is required!</span>
            <input type="submit" value="submit" />
        </form>
    </div>
    <h5>For more - <a href="https://code-sample.com" target="_blank"> Click this link..</a></h5>
  </body>

</html>
/* Put your css in here */