Solving Sun Intensity Problem: 685W/m^2 in 6.5 Days

[slaw155]

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?

 

[NascentOxygen]

To spot your error we need to see your working.

Show us your equation involving just one unknown, viz., time

If you include units along with magnitudes in all your equations, you will usually see where you are making mistakes, because you can cancel units just as you can cancel numbers.

 

[slaw155]

thanks solved it