Make a cylindrical oil drum out of iron sheet, with a bottom diameter of 6 decimeters and a height of 10 decimeters. What is the minimum square decimeter of iron sheet used to make this oil barrel?
用铁皮制作一个圆柱形油桶，底面直径6分米，高10分米．制作这个油桶至少要用铁皮多少平方分米？
<gadget id="calculator">3.14 * 6 * 10</gadget>
<output>188.4</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 * 2</gadget>
<output>56.52</output>

<gadget id="calculator">188.4 + 56.52</gadget>
<output>244.92</output>

<result>244.92</result>