Question

已知1-1/2=1/2,1/2-1/3=1/6 ,1/3-1/4=1/12 ,1/4-1/5=1/20,你能很快算出1/

Answer 1

把题目的4个式子左右2边分别相加,得到：

(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)=1/2+1/6+1/12+1/20

即：

1/2+1/6+1/12+1/20

=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)

=1-1/5

=4/5