1又2/3+2又2/15+3又2/35+.+11又2/483+12又2/575

原式=1+2+3+。。。+11+12+2/3+2/15+2/35+。。。+2/483+2/575=(1+12)*12/2+2*(1/3+1/15+1/35+。。。+1/483+1/575)=78+2*[1/(1*3)+1/(3*5)+1/(5*7)+。。。1/(21*23)+1/(23*25)]=78+2*1/2*(1/1-1/3+1/3-1/5+1/5-1/7+。。。+1/21-1/23+1/23-1/25)=78+(1-1/25)=78+24/25=78又24/25