1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10 =(1/2+1/3+1/6)+(1/4+1/5+1/10)+1/7+1/8+1/9 =1+11/20+1/8+1/7+1/9 =1+27/40+1/9+1/7 =1+283/360+1/7 =1+2341/2520 =4861/2520