Minmin washes some potatoes in a cylindrical container with a bottom radius of 20cm. The original water depth is 30cm. After taking out the potatoes, the water level drops by 3cm. What is the volume of these potatoes.
敏敏把一些土豆放在底面半径是20cm的圆柱形容器里清洗，原来水深30cm，拿出土豆后，水面下降了3cm．这些土豆的体积是多少．
<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>