What is the reciprocal of the sum of prime numbers up to 10?
10以内质数的和的倒数是多少．
<gadget id="calculator">2 + 3 + 5 + 7</gadget>
<output>17</output>

<gadget id="calculator">1 / 17</gadget>
<output>1/17 = around 0.058824</output>

<result>1/17 = around 0.058824</result>