Question

1又1/2+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42=?（

Answer 1

1又1/2+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42

=1+1/2+2+1/6+3+1/12+4+1/20+5+1/30+6+1/42

=(1+2+3+4+5+6)+(1/2+1/6+1/12+1/20+1/30+1/42)

=21+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)

=21+(1-1/7)

=21+6/7

=21又6/7