简便运算：1/2+（-1/6）+(-1/12)+（-1/20)+(-1/30)+(-1/42)=?

1/2+（-1/6）+(-1/12)+（-1/20)+(-1/30)+(-1/42)
=1/2+(1/3-1/2)+(1/4-1/3)+(1/5-1/4)+(1/6-1/5)+(1/7-1/6)
=1/2+1/3-1/2+1/4-1/3+1/5-1/4+1/6-1/5+1/7-1/6
=1/7