86分之1+8686分之303+868686分之90909+86868686分之11111111+8686868686分之1919191919

原式=1/86+3*101/86*101+9*10101/86*10101+11*1010101/86*1010101+19*101010101/86*101010101 =1/86+3/86+9/86+11/86+19/86 =(1+3+9+11+19)/86 =43/86 =1/2