Question

二分之一加六分之一加十二分之一加.一直加到九千九百分之一的和等于多少

Answer 1

1/2+1/6+1/12+1/20+…+1/9900

=1/2+1/(2*3)+1/(3*4)+1/(4*5)+…+1/(99*100)

=1/2+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+…+(1/99-1/100)

=1/2+1/2-1/100=99/100