A glass fish tank with a square bottom and a side length of 5 decimeters, and a water depth of 3 decimeters, a stone is submerged in it, and the water level rises by 4 centimeters. Find the volume of the stone.
一个底面为正方形，边长为5分米的玻璃鱼缸，水深3分米，把一个石块浸没其中，水面上升了4厘米．求石块的体积．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">5 * 5 * (2/5)</gadget>
<output>10</output>

<result>10</result>