(1/2)+(1/3+2/3)+(1/4+2/4+3/4)+(1/5+2/5+3/5+4/5)=(1/2)+1+(1+2+3)/4+(1+2+3+4)/5=3/2+6/4+10/2=3/2+3/2+5=3+5=8.
5
