In a cylindrical bucket with a bottom radius of 20cm, there is a steel cylinder with a bottom radius of 10cm that is completely submerged in the water. When the steel is taken out of the bucket, the water level in the bucket drops by 3cm. Find the length of this piece of steel centimeter?
在一个底面半径是20cm的圆柱形水桶里，有一个底面半径为10cm的圆柱体钢材完全浸没在水里，当钢材从桶里取出后，桶里的水面下降了3cm，求这段钢材长多少厘米？
<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

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

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">3_768 / 314</gadget>
<output>12</output>

<result>12</result>