The article Do Californian’s Really Use 20 Billion Plastic Bags Per Year? has been updated.  The text was clarified in a number of areas, including the insertion of equations showing how to perform calculations, as well as footnotes to fully document all of the sources of information.  We still maintain that the 20 billion Plastic Carryout Bag number is erroneous and the true number of plastic bags used is closer to 9 to 10 billion per year.