A cylindrical tin bucket without a lid has a bottom diameter of 30 cm and a height of 45 cm. How many square centimeters of tin is needed to make such a bucket?
一个无盖的圆柱形铁皮水桶，底面直径是30厘米，高是45厘米，做一个这样的水桶要用多少平方厘米铁皮？
<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>