24 o'clock: 4, 4, 7, 7.
24点：4,4,7,7．
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">4 - (4/7)</gadget>
<output>24/7 = around 3.428571</output>

<gadget id="calculator">7 * (24/7)</gadget>
<output>24</output>

<result>24</result>