[tex]1 \ kWh = 1 \ kW \cdot 1 \ h =1000 \ W\cdot3600 \ s = 3 \ 600 \ 000 \ J = 3,6\cdot10^{6} \ J\\\\1 \ J = \frac{1}{3,6}\cdot10^{-6} \ kWh = 0,2(7)\cdot10^{-6} \ kWh \approx0,28\cdot10^{-6} \ kWh[/tex]
