There is a rectangular parallelepiped of fiberglass with a length of 40 cm, a width of 20 cm, and a height of 10 cm. A stone is placed in it and filled with water. When the stone is picked up, the water level drops by 4 cm. What is the volume of this stone?
有一个长方体的玻璃钢，长是40厘米，宽是20厘米，高是10厘米，里面放入一块石头，并装满水，当石头捞起来时，水面下降了4厘米．这块石头的体积是多少？
<gadget id="calculator">40 * 20 * 4</gadget>
<output>3_200</output>

<result>3_200</result>