(1-1/2^2)(1-1/3^2)--------(1-1/2003^2)
=[(2^2-1)/2][(3^2-1)/3]-----[(2003^2-1)/2003^2]
=[(2-1)(2+1)/2*2][(3-1)(3+1)/3*3]------[(2003-1)(2003+1)/2003*2003]
=[(1*3)/2*2][(2*4)/3*3][(3*5)/4*4]------[2002*2004/2003*2003]
=(1/2)*(2004/2003)
=1002/2003
(1-1/2^2)(1-1/3^2)--------(1-1/2003^2)
=[(2^2-1)/2][(3^2-1)/3]-----[(2003^2-1)/2003^2]
=[(2-1)(2+1)/2*2][(3-1)(3+1)/3*3]------[(2003-1)(2003+1)/2003*2003]
=[(1*3)/2*2][(2*4)/3*3][(3*5)/4*4]------[2002*2004/2003*2003]
=(1/2)*(2004/2003)
=1002/2003