If the radius of a circle is 5 meters, what is its circumference in meters? (π takes 3.14)
已知圆的半径是5米，它的周长是多少米．(π取3.14)
<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<result>31.4</result>