Question

根据算式2分之1＝(1×2)分之1＝1－2分之1,

Answer 1

1/2+1/6+1/12+1/20+1/30

=1/（1*2）+1/（2*3）+1/（3*4）+1/（4*5)+1/(5*6)

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

=1-1/6

=5/6