1+（1/2-1）+（1/4-1/3）+（1/5-1/4）+……+（1/2009-1/2008）+(1/2010+1/2009)
=1-1+1/2-1/2+1/3+……+1/2008-1/2009+1/2009+1/2010
=1/2010