Untitled

<body ng-app="LandingApp">

    <form ng-controller="LandingApp">
        <input type="number" ng-model="numeroaltrepagine">{{numeroaltrepagine}}</input>
        <b>TOTALE</b><br/>
        {{totale() | currency}}
    </form>

    <b>TOTALE</b>


</body>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.1/angular.min.js"></script>
<script src="js/main.js"></script>

var LandingApp = angular.module('LandingApp',[]);

$scope.primapagine = 150;
$scope.altrepagine = 90;
$scope.numeroaltrepagine = 1;

$scope.totale = function(){
    return $scope.altrepagine * $scope.numeroaltrepagine;
}

<form ng-controller="numberpages">