1-2的2次方分之一)(1-3的二次方之一)……(1-2008的2次方分之一}1-2009的二次方分之一)
=(1-1/2)(1+1/2)(1-1/3)(1+1/3)(1-1/4)(1+1/4)……(1-1/2008)(1+1/2008)(1-1/2009)(1+1/2009)
=1/2×3/2×2/3×4/3×3/4×5/4×4/5……2007/2008×2009/2008×2008/2009×2010/2009
=1/2×2010/2009
=1005/2009