cylindrical iron drum without a lid, the diameter and height of the bottom surface are 6 decimeters, at least how much iron sheet should be used?
一个无盖的圆柱体铁桶，底面直径和高都是6分米，至少要用多少铁皮？
<gadget id="calculator">3.14 * 6 * 6</gadget>
<output>113.04</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<gadget id="calculator">113.04 + 28.26</gadget>
<output>141.3</output>

<result>141.3</result>