1/1×2+1/2×3+1/3×4+1/4×5+···+1/98×99+1/99×100 要过程在线等

1/1×2+1/2×3+1/3×4+1/4×5+···+1/98×99+1/99×100 要过程
在线等

1/1×2+1/2×3+1/3×4+1/4×5+···+1/98×99+1/99×100
=1-1/2+1/2-1/3+1/3-1/4+……+1/99-1/100
=1-1/100
=99/100