a※b=(a-b)/ab=1/b-1/a
2※1+3※2+4※3+.+2008※20007+2009※200
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/2007-1/2008)+(1/2008-1/2009)
=1-1/2009
=2008/2009