1/1x2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100
问题描述：
1/1x2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100
用简便运算.
答
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5******+1/98-1/99+1/99-1/100
=1-1/100
=99/100