20 students form a circle to play games on the playground. The distance between two adjacent students is 2 meters. What is the circumference of the circle in meters?
20名同学在操场上围成一个圈做游戏，每相邻两个同学之间的距离是2米，这个圈的周长是多少米？
<gadget id="calculator">2 * 20</gadget>
<output>40</output>

<result>40</result>