The length of a side of a cube container is 3 decimeters measured from the inside, and the depth of water in the container is 1.5 decimeters. Put a stone into the water (all submerged), then the depth of the water is 2 decimeters. What is the volume of the stone in cubic decimeters?
一个正方体容器从里面量棱长为3分米，容器水深1.5分米．把一块石头放入水中(全部浸没)，这时水深2分米．石头体积是多少立方分米？
<gadget id="calculator">2 - 1.5</gadget>
<output>0.5</output>

<gadget id="calculator">3 * 3 * 0.5</gadget>
<output>4.5</output>

<result>4.5</result>