Congcong put some potatoes in a cylindrical container with a bottom radius of 20cm to wash them. After all the potatoes were immersed in water, the water depth was 30cm. After taking out the potatoes, the water level dropped by 3cm. What is the volume of the potatoes?
聪聪把一些土豆放在底面半径是20cm的圆柱形容器里清洗，土豆全部浸入水中后水深30cm，拿出土豆后，水面下降了3cm，土豆的体积是多少？
<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>