Including the start and end date in the calculation, there are 549 days between those two dates.
180 days from September 14, 2011 is March 23, 2011.
Adding 180 days to September 20, 2010 gives March 19, 2011.
Adding 180 days to September 17, 2010 gives March 16, 2011.
The 29th of March 2010 was 185 days before the 30th of September 2010 and the 3rd of April 2011 was 185 days after it.
115 days from November 29 2010 to March 24 2011.
333 days from 17 March 2010 to 13 February 2011.
189 days before September 6 2010 is Monday, March 1, 2010.
Adding 180 days to March 18, 2010 gives September 14, 2010.
Adding 180 days to March 30, 2011 gives September 26, 2011.
Between October 24, 2010 and March 1, 2011 there are 128 days.
Between December 4, 2010 and March 11, 2011 there are 97 days.
September 27 2010 is 187 days away (from today March 24th).