(1/(1*2))+(1/(2*3))+(1/(3*4))+...+(1/(2011*2012)).
(1/(1*2))+(1/(2*3))+(1/(3*4))+…+(1/(2011*2012))．
<gadget id="calculator">1 / 2_012</gadget>
<output>1/2_012 = around 0.000497</output>

<gadget id="calculator">1 - (1/2_012)</gadget>
<output>2_011/2_012 = around 0.999503</output>

<result>2_011/2_012 = around 0.999503</result>