To make a pair of cylindrical iron buckets without a cover, the height is 12 cm, and the bottom diameter is 20 cm. How many square centimeters of iron are used?
做一对无盖的圆柱形铁皮水桶，高12厘米，底面直径20厘米，用铁皮多少平方厘米？
<gadget id="calculator">3.14 * 20 * 12</gadget>
<output>753.6</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">753.6 + 314</gadget>
<output>1_067.6</output>

<gadget id="calculator">1_067.6 * 2</gadget>
<output>2_135.2</output>

<result>2_135.2</result>