Fill water into a cuboid container with a length of 2 decimeters and a width of 1 decimeter. When the water in the container appears to be square for the second time, how many liters of water will be injected in total?
向一个长2分米，宽1分米的长方体容器注水，当容器中的水第二次出现相对的面是正方形时，共注水多少升．
<gadget id="calculator">2 * 1 * 2</gadget>
<output>4</output>

<result>4</result>