Lets try to understand Ng-bind with dynamic calculation, so we are going to add two number which will be input by user, taking two textbox and assigning them ng-model="val1"
and ng-model="val2"
and the default value of val1 and val2 is 0 as $scope.val1 = 0; $scope.val2 = 0;
Also created one function "sum" which will be called on-change of textboxes so once user type in textbox sum, fuction gets called which will add the val1 and val2 and store in the $scope.result variable and this variable is bind with the span below the textboxes.