There is a big clock hanging in the lobby of the hotel. The length of its minute hand is 5dm. What is the distance traveled by the tip of the minute hand in one revolution in dm?
饭店的大厅内挂着一只大钟，它的分针长5dm，这根分针的尖端转动一周所走的路程是多少dm？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">3.14 * 10</gadget>
<output>31.4</output>

<result>31.4</result>