An iron drum with a length of 5dm, a width of 4dm, and a height of 3dm contains water at a height of 1dm. A stone is placed in the water and the water rises to 2.5dm. What is the volume of the stone?
一个长5dm，宽4dm，高3dm的铁桶装有1dm高的水，放入一块石头的水面升高到2.5dm，石头的体积是多少？
<gadget id="calculator">2.5 - 1</gadget>
<output>1.5</output>

<gadget id="calculator">5 * 4 * 1.5</gadget>
<output>30</output>

<result>30</result>