Calculation: (1/2)+(1/6)+(1/12)+(1/20)+(1/30)+(1/42)+...+(1/156).
计算：(1/2)+(1/6)+(1/12)+(1/20)+(1/30)+(1/42)+…+(1/156)．
<gadget id="calculator">1 / 13</gadget>
<output>1/13 = around 0.076923</output>

<gadget id="calculator">1 - (1/13)</gadget>
<output>12/13 = around 0.923077</output>

<result>12/13 = around 0.923077</result>