How many square centimeters of iron sheets are needed to make a pair of cylindrical iron buckets with a height of 24 cm and a bottom diameter of 20 cm?
做一对高是24厘米，底面直径是20厘米的无盖圆柱形的铁皮水桶，至少需要铁皮多少平方厘米？
<gadget id="calculator">3.14 * 20 * 24</gadget>
<output>1_507.2</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

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

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

<gadget id="calculator">1_507.2 + 314</gadget>
<output>1_821.2</output>

<gadget id="calculator">1_821.2 * 2</gadget>
<output>3_642.4</output>

<result>3_642.4</result>