Adding 180 days to December 18, 2010 gives June 16, 2011.
The day that is 180 days after 31 December 2011 (the 180th day of 2012) is 28 June 2012.
Adding 180 days to March 18, 2010 gives September 14, 2010.
Adding 180 days to November 6, 2010 gives May 5, 2011.
180 days after June 9th, 2011 would be Tuesday December 6th, 2011.
Subtracting 63 days from December 31, 2010 gives October 29, 2010.
Adding 60 days to December 2, 2010 gives January 31, 2011.
56 days from Oct 24 2010 will be Sunday, December 19, 2010.
There are 365 days in the year 2010. Therefore, the 364th day of the year is December 30, 2010.
March 31
Adding 120 days to August 20, 2010 gives December 18, 2010.
Adding 90 days to September 30, 2010 gives December 29, 2010.