A prime number p, so that p+2 and p+4 are prime numbers at the same time, then (1/(p))+(1/(p+2))+(1/(p+4))=what.
一个质数p，使得p+2，p+4同时都是质数，则(1/(p))+(1/(p+2))+(1/(p+4))=多少．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/3) + (1/5) + (1/7)</gadget>
<output>71/105 = around 0.67619</output>

<result>71/105 = around 0.67619</result>