The circumference of the bottom of the gasoline barrel is 6.28 meters and the height is 3 meters. How many square meters of iron sheet is needed to make such a gasoline barrel?
汽油桶的底面周长是6.28米，高是3米．做一个这样的汽油桶至少需要多少平方米的铁皮？
<gadget id="calculator">6.28 * 3</gadget>
<output>18.84</output>

<gadget id="calculator">6.28 / 3.14 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1 * 2</gadget>
<output>6.28</output>

<gadget id="calculator">18.84 + 6.28</gadget>
<output>25.12</output>

<result>25.12</result>