3^x的尾数x=4n+1, 尾数为3x=4n+2, 尾数为9x=4n+3, 尾数为7x=4n,尾数为12009=4n+1,3^2009尾数为32010=4n+2,3^2009尾数为92011=4n+3,3^2009尾数为73^2011-3^2010-3^2009的尾数为7-9-3=-5,借位后为10+(-5)=5尾数为5...