(1-1/2^2)*(1-1/3^2)...(1-1/10^2)
=[(1+1/2)*(1-1/2)] * [(1+1/3)*(1-1/3)] ...[(1+1/10)*(1-1/10)]
=[(1+1/2)*(1+1/3) ...(1+1/10)] * [(1-1/2)*(1-1/3) ...(1-1/10)]
=[(3/2) * (4/3) * (5/4) ...(11/10)] * [(1/2) * (2/3) * (3/4) ...(9/10)]
=(11/2) * (1/10)
=11/20