A cylindrical bucket with a height of 40 cm and a base radius of 20 cm is half filled with water. Xiaohong completely submerges a stone in the bucket, and the water level rises by 3 cm. What is the volume of the stone?
一个高40厘米的圆柱形水桶，底面半径是20厘米，这个桶盛有半桶水．小红将一块石头完全浸入水桶中，水面比原来上升了3厘米，这块石头的体积是多少？
<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">3.14 * 400 * 3</gadget>
<output>3_768</output>

<result>3_768</result>