计算1/1*2+1/2*3+1/4*5+……+1/2004*2005.
问题描述：
计算1/1*2+1/2*3+1/4*5+……+1/2004*2005.
答
题目应为1/1*2+1/2*3+1/3*4+1/4*5+……+1/2004*2005吧!
原式=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+……+1/2004-1/2005
=1-1/2005
=2004/2005