It is known that 1*3=1*2*3, 3*4=3*4*5*6, then (5*4)/2=how much.
已知1※3=1*2*3，3※4=3*4*5*6，那么(5※4)/2=多少．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">5 * 6 * 7 * 4</gadget>
<output>840</output>

<result>840</result>