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

app.controller('MainCtrl', function($scope) {
$scope.name = 'World';
$scope.count = 0;

$scope.total = function(count){
var total =
// I want to parseFloat the $scope.td1 + the current count.
// How does the syntax look when you concat ng-model.
parseFloat($scope.td1 + count || 0) +
parseFloat($scope.td2 + count || 0) +
parseFloat($scope.td3 + count || 0) +
parseFloat($scope.td4 + count || 0) +
parseFloat($scope.td5 + count || 0);
return total || 0;
}
});