(2/7) of a number is the smallest prime number, what is this number.
一个数的(2/7)是最小的质数，这个数是多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">2 / (2/7)</gadget>
<output>7</output>

<result>7</result>