Question

十五分之一加上三十五分之一加上六十三分之一

Answer 1

1/3+1/15+1/35+1/63+1/99+1/143
=1/2x[(1-1/3)+(1/3-1/5)+(1/5-1/7)+(1/7-1/9)+(1/9-1/11)+(1/11-1/13)]
=1/2x(1-1/13)
=1/2x12/13
=6/13