Question

2分之3+6分之7+12分之13+20分之21+30分之31+42分之43=

Answer 1

=(1+1-1/2)+(1+1/2-1/3)+(1+1/3-1/4)+(1+1/4-1/5)+(1+1/5-1/6)+(1+1/6-1/7)

=6+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)

=7-1/7

=48/7