A fence is built around a circular flower bed with a radius of 20 meters. How many meters is the fence?
在一块半径20米的圆形花坛周围围一圈篱笆．篱笆长多少米？
<gadget id="calculator">3.14 * 20 * 2</gadget>
<output>125.6</output>

<result>125.6</result>