A joule is equal to one watt per second and so we must find out how many seconds are in two hours.
A shortcut you can use is remove the zeros and multiplying the remaining numbers before adding the the zeros back to the total of your result
6 x 6 x 2 = 72 and thus
60 x 60 x 2 = 7200
72 x 15 = 1080 and thus
7200 x 1500 = 10800000 joules
one mega joule equals one million joules
So we can simplify things and say 10.8 MJ
