A cylindrical measuring cup has a bottom diameter of 8 cm and a water depth of 10 cm. Now submerge an irregular stone in a measuring cup, the depth of water is 15 cm, what is the volume of this stone?
一个圆柱形量杯的底面直径为8厘米，水深为10厘米．现在把一块不规则的石头浸没在量杯里，水深为15厘米，这块石头的体积是多少？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 16 * 5</gadget>
<output>251.2</output>

<result>251.2</result>