To make a cylindrical bucket with a bottom diameter of 6 decimeters and a height of 10 decimeters, at least how many square decimeters of iron sheet is needed to make such a bucket.
做一个无盖的圆柱形水桶底面直径是6分米，高10分米，做这样的水桶至少需要多少平方分米的铁皮．
<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">3.14 * 6 * 10</gadget>
<output>188.4</output>

<gadget id="calculator">28.26 + 188.4</gadget>
<output>216.66</output>

<result>216.66</result>