Leap year 3/30
Non leap year 3/31
180 days from October 11th, 2011 would be Sunday April 8th, 2012.
Adding 180 days to October 29, 2010 gives April 27, 2011.
Adding 180 days to October 9, 2010 gives April 7, 2011.
180 days after October 4th, 2011 is Sunday April 1st, 2012.
October 13, 2010 + 180 days = April 11, 2011.
Heading into a non-leap year, adding 180 days to October 18 gives April 16 of the following year. Heading into a leap year, adding 180 days to October 18 gives April 15 of the following year.
Adding 180 days to April 5, 2011 gives October 2, 2011.
Adding 180 days to April 30, 2006 gives October 27, 2006.
Adding 180 days to October 4, 2010 gives April 4, 2011.
Adding 180 days to April 11, 2011 gives October 8, 2011.
Adding 180 days to October 6, 2010 gives April 4, 2011.
In any given year, adding 180 days to April 28 gives October 25.