To make an uncovered tin bucket with a bottom diameter of 6 decimeters and a height of 8 decimeters, how many square decimeters of iron is needed at least?
做一个底面直径是6分米、高8分米的无盖铁皮水桶，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 * 8</gadget>
<output>150.72</output>

<gadget id="calculator">28.26 + 150.72</gadget>
<output>178.98</output>

<result>178.98</result>