1/(1990/1+1991/1+1992/1+...+1999/1)等于多少
问题描述:
1/(1990/1+1991/1+1992/1+...+1999/1)等于多少
答
1/(1990/1+1991/1+1992/1+...+1999/1)
=1/【(1990+1999)*10/2)】
=1/19945