(1-1/2^2)*(1-1/3^2)*(1-1/4^2)……(1-1/2010^2)
=(1+1/2)(1-1/2)(1+1/3)(1-1/3)(1+1/4)(1-1/4)×……×(1+1/2010)(1-1/2010)
=3/2×4/3×5/4×……×2011/2010×1/2×2/3×3/4×……×2009/2010
=2011/2×1/2010
=2011/4020
(1-1/2^2)*(1-1/3^2)*(1-1/4^2)……(1-1/2010^2)
=(1-1/2)(1+1/2)(1-1/3)(1+1/3)(1-1/4)(1+1/4)……(1-1/2010)(1+1/2010)
=(1/2)(3/2)(2/3)(4/3)(3/4)(5/4)......(2008/2009)(2010/2009)(2009/2010)(2011/2010)
=(1/2)(2011/2010)
=2011/4020