Sun emits 153.6 x 10^15 J of energy onto a region that is 20km by 20km in area. The intensity of the sun on this region is 685W/m^2. How many days would it take for the sun to put that amount of energy onto the region? I went intensity = power/area and got to a time of some 44000seconds, however this does not convert to the correct number of days of 6.5days. Where have I gone wrong?