Calculation: (1/3)+(1/15)+(1/35)+(1/63).
计算：(1/3)+(1/15)+(1/35)+(1/63)．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 35</gadget>
<output>1/35 = around 0.028571</output>

<gadget id="calculator">1 / 63</gadget>
<output>1/63 = around 0.015873</output>

<gadget id="calculator">(1/3) + (1/15) + (1/35) + (1/63)</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>