When an electrical appliance whose power usage is X watts is run for Y seconds, it uses X × Y joules of energy. The energy unit used by electrical utilities in their monthly bills is the kilowatt-hour (kWh, that is, 1 kilowatt used for 1 hour). How many joules are there in a kilowatt-hour? If electricity costs $0.09 per kilowatt-hour, how much does it cost per megajoule?