(1/3), (1/6), (1/12), (1/20)... What is the sum of the first 30 numbers?
(1/3)，(1/6)，(1/12)，(1/20)…前30个数的和是多少．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 31</gadget>
<output>1/31 = around 0.032258</output>

<gadget id="calculator">(1/2) - (1/31)</gadget>
<output>29/62 = around 0.467742</output>

<gadget id="calculator">(1/3) + (29/62)</gadget>
<output>149/186 = around 0.801075</output>

<result>149/186 = around 0.801075</result>