How many square centimeters of iron sheets are needed to make a pair of cylindrical buckets without a lid with a bottom diameter of 30 cm and a height of 45 cm?
做一对底面直径30厘米，高45厘米的无盖圆柱形水桶，至少需要铁皮多少平方厘米？
<gadget id="calculator">3.14 * 30 * 45</gadget>
<output>4_239</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">15 ** 2</gadget>
<output>225</output>

<gadget id="calculator">3.14 * 225</gadget>
<output>706.5</output>

<gadget id="calculator">4_239 + 706.5</gadget>
<output>4_945.5</output>

<result>4_945.5</result>