(1/3)+(1/(3+6))+(1/(3+6+9))+...+(1/(3+6+9+...+90))=how much.
(1/3)+(1/(3+6))+(1/(3+6+9))+…+(1/(3+6+9+…+90))=多少．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 34</gadget>
<output>1/34 = around 0.029412</output>

<gadget id="calculator">1 - (1/34)</gadget>
<output>33/34 = around 0.970588</output>

<gadget id="calculator">(2/3) * (33/34)</gadget>
<output>11/17 = around 0.647059</output>

<result>11/17 = around 0.647059</result>