To make a cylindrical iron bucket without a cover, the height is 30cm, and the diameter of the bottom is 10cm. How much iron is needed to make this bucket?
做一个无盖的圆柱形铁皮水桶，高30cm，底面直径是10cm，做这个水桶至少需要多少铁皮？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<gadget id="calculator">3.14 * 10 * 30</gadget>
<output>942</output>

<gadget id="calculator">78.5 + 942</gadget>
<output>1_020.5</output>

<result>1_020.5</result>