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

<gadget id="calculator">2_005 * (1/2_005)</gadget>
<output>1</output>

<result>1</result>