a 60-watt light bulb uses 60 watt hours of electricity in 1 hour. Suppose everyone in the United States lef one unneeded 60 watt light bulb on for one hour everyday for a year.

Electricity is billed in kilowatt hours. So 60 watt hours is equal to sixty divided by one thousand. Express the electricity used by a 60 watt light bulb in one hour in kilowatt hours in scientific notation.