:(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/9^2)(1-1/10^2)
=(1+1/2)(1-1/2)+(1+1/3)(1-1/3)..(1+1/10)(1-1/10)
=1/2*3/2*2/3*4/3*3/4*5/4..9/10*11/10=11/20
设四个连续自然数为a,a+1,a+2,a+3,(a+1)(a+2)-a(a+3)=2>0
:(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/9^2)(1-1/10^2)
=(1+1/2)(1-1/2)+(1+1/3)(1-1/3)..(1+1/10)(1-1/10)
=1/2*3/2*2/3*4/3*3/4*5/4..9/10*11/10=11/20
设四个连续自然数为a,a+1,a+2,a+3,(a+1)(a+2)-a(a+3)=2>0