Question

二分之一减六分之一减十二分之一减二十分之一减三十分之一减四十二分之一简便运算

Answer 1

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

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

=1/7