(2005/(1*2))+(2005/(2*3))+(2005/(3*4))+(2005/(4*5))+…+(2005/(2004*2005) ) = how much.
(2005/(1*2))+(2005/(2*3))+(2005/(3*4))+(2005/(4*5))+…+(2005/(2004*2005))=多少．
<gadget id="calculator">1 / 2_005</gadget>
<output>1/2_005 = around 0.000499</output>

<gadget id="calculator">1 - (1/2_005)</gadget>
<output>2_004/2_005 = around 0.999501</output>

<gadget id="calculator">2_005 * (2_004/2_005)</gadget>
<output>2_004</output>

<result>2_004</result>