Wrap a circle of trademark paper on the side of a cylindrical battery with a bottom diameter of 4 cm and a height of 8 cm. If the joint is not counted, at least how many square centimeters of paper is needed.
给一节底面直径是4厘米，高是8厘米的圆柱形电池的侧面包上一圈商标纸，如果不算接头处，至少要多少平方厘米的纸．
<gadget id="calculator">3.14 * 4 * 8</gadget>
<output>100.48</output>

<result>100.48</result>