The diameter of a round tea tray is 3 decimeters, and a circle of label paper is pasted along its edge, how long is the label paper required?
一个圆形茶盘的直径是3分米，沿着它的边沿贴一圈商标纸，需要多长的商标纸？
<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<result>9.42</result>