Question

计算：2分之1+6分之1+12分之1+20分之1+30分之1+42分之1 等于多少?算式也要

Answer 1

1/2+1/6+1/12+1/20+1/30+1/42

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

=1-1/7=6/7