1. The problem statement, all variables and given/known data How much would the rest energy of a 1.0 Kg mass cost at the typical utility rate of $0.60/ kWh? 2. Relevant equations E=mc^2 3. The attempt at a solution Heres what somone told me from another website: "The rest energy of a mass is the energy calculated by E=mc^2 when the mass is at rest. E = (3E8 m/s)^2 * 1kg = 9E16 J 1 kWh = (1000 J/s)(3600 s) = 3.6E6 J Energy * Cost/Energy = Cost (9E16 J) * (1 kWh / 3.6E6 J) * ($0.60 kWh) = 15 billion dollars" but i dont understand the last part, where they multiply (9E16 J) * (1 kWh / 3.6E6 J) * ($0.60 kWh). The eprson said Energy * Cost/Energy = Cost, so wouldnt that just be (9E16 J)(($0.60 kWh)/(9E16 J))?