(A) 0.99
(B) 1
(C) 99
(D) 0.9答案: (A)
解释:
S = 1/1*2 + 1/2*3 + 1/3*4 + ..... + 1/99*100
= (1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + .... + (1/99 - 1/100)
= (1 + 1/2 + 1/3 .... 1/99) - (1/2 + 1/3 + 1/4 ... 1/100)
= 1 - 1/100
= 99/100
= 0.99
这个问题的测验