1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+……+1/(2009*2010)
=(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+……+(1/2009-1/2010)
=1/2-1/2010
=1004/2010
=502/1005