angularjs_directive_binding
HTML
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>
<div ng-app="" ng-init="quantity=1;price=5">
Quantity: <input type="number" ng-model="quantity"></input>
Costs: <input type="number" ng-model="price"></input> <br />
Total in dollar: {{ quantity * price }}
</div>