Question

1+2分之1+6分之1+12分之1+20分之1+30分之1+42分之1+56分之1.+132分之1=?

Answer 1

1+1/2+1/6+1/12+.+1/132

=1+(1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/11-1/12)

=1+1-1/2+1/2-1/3+1/3-1/4+.+1/11-1/12

=2-1/12

=1又11/12