The bottom area of a cuboid tank is 400 square centimeters, and the height of the original water surface in the tank is 10 cm. After putting a small stone (the stone is completely immersed in the water, the water is not full), the water level rises to 15 cm. Find the volume of the small stone.
一个长方体水槽的底面积是400平方厘米，槽内原水面高度10厘米，放入一块小石块后(石块完全浸入水中，水没有满出)，水面上升到15厘米．求小石块的体积．
<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<gadget id="calculator">400 * 5</gadget>
<output>2_000</output>

<result>2_000</result>