(2/(1*3))+(2/(3*5))+(2/(5*7))+…+(2/(2001*2003))+(2/(2003*2005) ).
(2/(1*3))+(2/(3*5))+(2/(5*7))+…+(2/(2001*2003))+(2/(2003*2005))．
<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>

<result>2_004/2_005 = around 0.999501</result>