一道巧算题目

问题描述:

一道巧算题目
(1+1/2)×(1+1/4)×(1+1/6)×(1+1/8)×(1+1/10)×(1-1/3)×(1-1/5)× (1-1/7)×(1-1/9)
PS:【/】是分数线,请用简便方法计算,给出2-3步即可

(1+1/2)×(1+1/4)×(1+1/6)×(1+1/8)×(1+1/10)×(1-1/3)×(1-1/5)× (1-1/7)×(1-1/9)
=(1+1/2)×(1-1/3)×(1+1/4)×(1-1/5)×.)×(1+1/10)
=1×1×1×1×11/10
=11/10