JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.angularjs.org/1.2.16/angular.min.js"></script>
<div ng-controller="MainCtrl">
<div ng-repeat="row in rows" ng-controller="RowCtrl">
        <input type="text" class="form-control" ng-model="row.unit_price">
        <input type="text" class="form-control" ng-model="row.quantity"> 
        <strong>&euro; {{total | number:2}} ex.</strong>
        <small>&euro; {{total*1.21 | number:2}} in.</small>
</div>
</div>

JavaScript

var app = angular.module('myApp', []);
app.controller('RowCtrl', function ($scope) {
    $scope.$watchCollection('[unit_price, quantity]', function(newValues) {
        $scope.total = $scope.unit_price * $scope.quantity;
    });
});

app.controller('MainCtrl', function ($scope) {
    $scope.rows = ['1','2','3'];
});