A cylindrical oil barrel is 48 centimeters high and 20 centimeters in diameter at the bottom. How many square centimeters of iron sheet should be used to make this barrel?
一种圆柱形油桶，高48厘米，底面直径是20厘米，做这水桶至少要用铁皮多少平方厘米？
<gadget id="calculator">3.14 * 20 * 48</gadget>
<output>3_014.4</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100 * 2</gadget>
<output>628</output>

<gadget id="calculator">3_014.4 + 628</gadget>
<output>3_642.4</output>

<result>3_642.4</result>