row number for each table row created by dir-paginate angularJs

How can set row number for each table row created by dir-paginate angularJs. I use two way code but two way have incorrect and set error.

First way :

    <tr dir-paginate='customer in Customers| itemsPerPage: 10'>
        <td>{{rowNum=(rowNum+1)}}</td>
        <td>{{customer.fName}}</td>
        <td>{{customer.lName}}</td>
    </tr>

<script>
 (function(){
    var app = angular.module('customerApp', ['angularUtils.directives.dirPagination']);
    app.controller('customer', ['$scope', '$http',  function($scope, $http){
        $scope.rowNum = 1;
   }]);
})();
</script>

Second way :

<tr dir-paginate='customer in Customers| itemsPerPage: 10'>
        <td>{{getRowNum()}}</td>
        <td>{{customer.fName}}</td>
        <td>{{customer.lName}}</td>
    </tr>

<script>
 (function(){
    var app = angular.module('customerApp', ['angularUtils.directives.dirPagination']);
    app.controller('customer', ['$scope', '$http',  function($scope, $http){
        $scope.rowNum = 1;
        $scope.getRowNum = function(){
            return ++$scope.rowNum;
        };
   }]);
})();
</script>

Why i can't increment $scope.rowNum from function and ng-bind ?

I think {{$index+1}} should work

image with index + pagination -> {{(currentPage-1)*pageSize +$index+1}}