A stone is placed in a glass tank with a length of 80 cm and a width of 40 cm. At this time, the water depth is 30 cm. After the stone is taken out, the water depth is 25 cm. What is the volume of the stone in cubic decimeters?
在一个长为80厘米，宽为40厘米的玻璃缸中，放入一石块，这时水深为30厘米，取出石块后水深为25厘米，这块石块的体积是多少立方分米？
<gadget id="calculator">30 - 25</gadget>
<output>5</output>

<gadget id="calculator">5 / 1_000</gadget>
<output>1/200 = around 0.005</output>

<gadget id="calculator">80 * 40 * (1/200)</gadget>
<output>16</output>

<result>16</result>