There is a smart code for that. The typical area code is @<A,O,F>@. This code would be A=Area, O=Area from object, F=Don't add suffix.
If you want to specify the number of decimals to display, then use "@<A,O,T,3>@" (where 3 is the number of decimals).
If you want to use the "Large area format", use "@<A,O,T,2,T>@" where I used 2 for number of decimals. The 5th value specifies to use the alternate format (Hectares in metric)