Business Interview: How many gallons of gasoline sold today in the U.S.?

If you can answer this question through the process whole thought, I really appreciate it. Also, please let me know if you have other resources for business interviews. Thanks for the help!

Hmm, I'll check Google. Found a website that gives gasoline engines full in thousands of barrels per day. 9222 September 06. 9222 * 1000 * 42 gallons per barrel = 387,324,000 gallons per day. Not on today's figures, but the market size is a case to obtain an estimate. I also found some sample questions the case.