Question

二分之一加六分之一加十二分之一加.到一三十二分之一.

Answer 1

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

=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)

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

=1-1/6

=5/6