To answer this question, you need to understand how to convert a unit. In this case, the conversion would be milli meter to feet. Since it area(the unit is ^2), the conversion needs to be done twice.
The calculation would be:
(6.490^10^3 mm2) / (304.8mm/ft) / (304.8mm/ft) = 0.06985= 6.985* 10^-2 ft2
