To make an uncovered cylindrical bucket with a bottom area of 60cm in diameter and a height of 40cm, how many square centimeters of iron sheet are needed at least?
做一个没盖的圆柱形水桶，底面积直径60cm，高40cm，至少需要铁皮多少平方厘米？
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">30 ** 2</gadget>
<output>900</output>

<gadget id="calculator">3.14 * 900</gadget>
<output>2_826</output>

<gadget id="calculator">3.14 * 60 * 40</gadget>
<output>7_536</output>

<gadget id="calculator">2_826 + 7_536</gadget>
<output>10_362</output>

<result>10_362</result>