Calculation: (1/3)+(1/(3+5))+(1/(3+5+7))+...+(1/(3+5+7+...+21)).
计算：(1/3)+(1/(3+5))+(1/(3+5+7))+…+(1/(3+5+7+…+21))．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<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>

<gadget id="calculator">(1/2) * (12/13)</gadget>
<output>6/13 = around 0.461538</output>

<result>6/13 = around 0.461538</result>