This kind of method should not be in controller at all. If it is only a simple ToString
call, do it in the view directly.
If it is something more complex, do it in your ViewModel (the type you are passing to your strongly typed view) or create an extension method (e.g. as an extension on int
type) and call that method from the view directly - but only if it is a simple view related transformation.
If it is a more complex transformation involving any kind of business logic, do that in your controller or in your service layer (used by controller) before passing the data to view.