Adding values from array with AngularJS

Using javascript and AngularJS how would I go about adding the Hours values into a variable. I've tried simple JS that I do know (limited knowledge, still beginner) and no luck.

    <table class="table table-condensed table-striped table-hover">
                                                    <thead>
                                                        <tr>
                                                            <!--<td></td>-->
                                                            <td><a href="" ng-click="predicate= 'UserName'; reverse=!reverse">Employee <i class="fa fa-sort"></i></a></td>
                                                            <td><a href="" ng-click="predicate= 'TotalHours'; reverse=!reverse">Hours <i class="fa fa-sort"></i></a></td>
                                                            <td><a href="" ng-click="predicate= 'Date'; reverse=!reverse">Date <i class="fa fa-sort"></i></a></td>
                                                        </tr>
                                                    </thead>
                                                    <tbody>
                                                        <tr ng-repeat="jobhour in jobHours | orderBy:predicate:reverse">
                                                            <!--<td>{{$index + 1}}</td>-->
                                                            <td>{{jobhour.UserName}}</td>
                                                            <td>{{jobhour.AdminHours*1 + jobhour.FieldHours*1 + jobhour.OtherHours*1 + jobhour.TravelHours*1 | number:2}}</td>
                                                            <td>{{jobhour.Date | date:medium}}</td>
                                                        </tr>
                                                    </tbody>
                                                </table>

Above is the code for the ng-repeat on the table and you see I'm adding several values into that column already (this may be why I'm not sure on a simple way to approach this). The TOTAL value I'm trying to get is nothing more than a simple UI notification. I want to place this 'TOTAL SUM' into the label above next to Total Hours:

ANSWER FOR THIS SPECIFIC CODE:

Here's what I ended up doing and worked perfectly. Thanks for the help.

    function addArr(arr){
        var val = 0;
        for (var i = 0; i < arr.length; i++) {
            val += parseFloat(arr[i].AdminHours || 0) + parseFloat(arr[i].FieldHours || 0) + parseFloat(arr[i].TravelHours || 0) + parseFloat(arr[i].OtherHours || 0);
            //val += arr[i].AdminHours + arr[i].FieldHours + arr[i].TravelHours + arr[i].OtherHours;
        }
        $scope.totalHours = val;
    }