How can display a calculated field using ODK buid

1. What is the problem? Be very detailed.
I have captured a geoshape in my form and would like to display its area within the form. I am only familiar with ODK build for now so need a solution I can implement in ODK build. If it is not possible to show, is there a way to save this when submitting the form so the area is a field in aggregate?
2. What app or server are you using and on what device and operating system? Include version numbers.
I'm using ODK Collect and ODK Aggregate
3. What you have you tried to fix the problem?
I have put the area function in a format like this in the calculate field but keep getting zero as the answer. See my sample calculation. "area(/data/Farmdetails/farmarea)". am i referencing the data wrongly? strong text
4. What steps can we take to reproduce the problem?
Create a geoshape in ODK build and a numeric field, then try to set the value of the numeric or text object to the area of the geoshape so the user can see in odk collect?
5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.

I have a sample form i can share.

Hello @sparklord,

Welcome to the ODK forum! We're glad you're here. When you get a chance, please introduce yourself here.

I believe you will be able to display the calculated value by adding a note next to the calculation and just reference the value to that field. Please see the example of how it works on xls form:

test_tool.xlsx (12.3 KB)

Hope this helps,