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