In Team Forms, you can reference the response to almost any component in calculated fields—for example, to perform real-time calculations or logic while the user is filling out the form. However, one key exception is the submission number.
Why not?
The submission number is a special field that’s generated by the system and is not always immediately available when the user is filling out the form. This is especially important in scenarios where Team Forms is being used offline.
Because the next available submission number is determined by checking with the server, it can’t be known until the device has an internet connection. In many cases, the submission number is only assigned after the form is submitted and synced.
What does this mean?
This means that, unlike other fields, the submission number can’t be used in calculated fields, as it may not exist at the time the calculation is being performed.