title: convert unix epoch time to human readable time
body: <p>First I have an Unix epoch time  1270787111.</p>
  
  <p>Then based on this website:
  <a href="http://untangible.com/2009/01/covert-unix-epoch-dates-in-microsoft-excel-including-timezone-examples.html" rel="nofollow">http://untangible.com/2009/01/covert-unix-epoch-dates-in-microsoft-excel-including-timezone-examples.html</a>,
  I convert the number to be 40276.9758217592.
  Then I put the value into an Excel cell and convert it into "Date" format  to be : 4/8/10 23:25
  I do not know how this happens. How can the value 40926 be converted into 2010(year)04(month)08(day)? Is there any other programming way to convert an Unix epoch time into a human readable format time?</p>