If an irregular stone is submerged in a cuboid glass tank with a bottom area of 50 cm**2, the water level rises by 0.4 cm, what is the volume of the stone in cm**3.
把一块不规则的石块浸没到底面积是50厘米**2的长方体玻璃缸中，水面上升了0.4厘米，这块石块的体积是多少厘米**3．
<gadget id="calculator">50 * 0.4</gadget>
<output>20</output>

<result>20</result>