Think about it, do the math. (1/(1*2))+(1/(2*3))+(1/(3*4))+...+(1/(2008*2009)).
想一想，算一算．(1/(1*2))+(1/(2*3))+(1/(3*4))+…+(1/(2008*2009))．
<gadget id="calculator">1 / 2_009</gadget>
<output>1/2_009 = around 0.000498</output>

<gadget id="calculator">1 - (1/2_009)</gadget>
<output>2_008/2_009 = around 0.999502</output>

<result>2_008/2_009 = around 0.999502</result>