(1/2012-1)*(1/2011-1)*(1/2010-1)*(1/2009-1)*(1/2008-1)*.(1/2001-1)*(1/2000-1)
=(-2011/2012)(-2010/2011)*(-2009/2010)...(-2000/2001)(-1999/2000)
=1999/2012