Using the Row ID value in a calculated column quirk

Sharepoint has a quirk where it drops the [ ] around ID in the calculated value. This happens when either a new item is added to the list or I edit an existing item. The short-term fix is that every time a change is made, I have to manually go enter the brackets back around  ID but it’s hard to keep up with. Long-term fix is to use SharePoint Designer workflow.

Please see detail here.