The number B is (2/7) of the number A, the number C is (3/7) of the number B, and the number C is the number of A.
乙数是甲数的(2/7)，丙数是乙数的(3/7)，丙数是甲数的多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 * (2/7) * (3/7)</gadget>
<output>6/49 = around 0.122449</output>

<result>6/49 = around 0.122449</result>