100 pieces of the same small stones are put into a water glass with a length of 2 decimeters, a width of 5 cm, and a depth of 4 cm. The water level rises by 2.5 cm. What is the approximate cubic centimeter of each small stone?
100块同样的小石头放进一个长2分米，宽5厘米，深4厘米的水杯里，水面上升了2.5厘米，每块小石头大约多少立方厘米？
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">2.5 / 100</gadget>
<output>0.025</output>

<gadget id="calculator">20 * 5 * 0.025</gadget>
<output>2.5</output>

<result>2.5</result>