1×2×3／1加2×3×4／1加……加20×21×22／1
=（1×2/1-2×3／1加2×3/1-3×4／1加……加20×21/1-21×22／1）÷2
=（1×2/1-21×22／1）÷2
=（2/1-462/1）÷2
=462/230÷2
=462/115我的试卷答案上是115分之462，没过程462/115就是462分之115，你把分子、分母说反了哦，对不起，试卷上是462分之115462/115就是462分之115