In a cuboid tank with a length of 30 cm and a width of 20 cm, there is water at a depth of 15 cm. After a stone is taken out of the water, the water level drops by 4 cm. What is the volume of the stone?
在一个长30厘米，宽20厘米的长方体水箱中有15厘米深的水，先从水中取出一块石头后，水面下降了4厘米，石头的体积是多少？
<gadget id="calculator">30 * 20 * 4</gadget>
<output>2_400</output>

<result>2_400</result>