A cuboid glass water tank is 30 cm long, 20 cm wide, and 50 cm high. If water is poured into this water tank, when the shape of the water appears for the second time and the opposite surface is a square, how much water will be injected?
一个长方体玻璃水箱，长30厘米，宽20厘米，高50厘米，如果往这个水箱里注水，当水的形状第二次出现相对的面是正方形时，注入的水有多少？
<gadget id="calculator">20 * 30 * 30</gadget>
<output>18_000</output>

<result>18_000</result>