((1-(1/2))*(1-(1/3))*(1-(1/4)*…*(1-(1/2012)))*(1+(1/ 2))*(1+(1/3))*(1+(1/4))*…*(1+(1/2012)))=how much.
((1-(1/2))*(1-(1/3))*(1-(1/4))*…*(1-(1/2012)))*(1+(1/2))*(1+(1/3))*(1+(1/4))*…*(1+(1/2012)))=多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2_013 / 2_012</gadget>
<output>2_013/2_012 = around 1.000497</output>

<gadget id="calculator">(1/2) * (2_013/2_012)</gadget>
<output>2_013/4_024 = around 0.500249</output>

<result>2_013/4_024 = around 0.500249</result>