1/1×2＋1/2×3＋1/3×4＋……＋1/49×50简便计算,等于多少

Question

1/1×2＋1/2×3＋1/3×4＋……＋1/49×50
简便计算,等于多少

Answer 1

原式=1-1/2+1/2-1/3+1/3-1/4+……+1/48-1/49+1/49-1/50
=1-1/50
=49/50