=2/2+2/[(1+2)*2]+2/[(1+3)*3]+...+2/[(1+2000)*2000]
=2{1/2+1/(2*3)+1/(3*4)+...+1/(2000*2001)}
=2{1/2+1/2-1/3+1/3-1/4+...+1/2000-1/2001}
=2{1/2+1/2-1/2001}
=4000/2001
=2/2+2/[(1+2)*2]+2/[(1+3)*3]+...+2/[(1+2000)*2000]
=2{1/2+1/(2*3)+1/(3*4)+...+1/(2000*2001)}
=2{1/2+1/2-1/3+1/3-1/4+...+1/2000-1/2001}
=2{1/2+1/2-1/2001}
=4000/2001