Determine the cost of using 2 different electrical devices over the course of a month. - An item like a cellphone or something else that plugs in the wall. Use $.20 per kilowatt-hour as your base energy cost. I have no idea how to start this as this is a project we have to do as a prerequisite for a college course. I have been searching online and it looks like the only way to calculate this is to buy a $50 dollar Kill-o-watt. It would be great if one of you guys can help me with this without having to go out and buy something. Also my teacher said estimating is fine too.