First of all do you mean Pascal REAL? in that case use the unit real48 that comes with FPC. A Pascal REAL is 48 bits and is a legacy format.
Or do you mean REAL as used in other languages? ? In that case it depends on what they gave defined: it can be a single (4 bytes), double (8 bytes) or extended, which is either 8 or 10 bytes depending on platform.
Is there a more simple way to do it?Yes, use the default() intrinsic.