The minute hand of a clock is 40 mm long. What is the circumference of the minute hand in one revolution?
一只钟的分针长40毫米，这根分针的尖端移动一周的周长是多少毫米？
<gadget id="calculator">3.14 * 2 * 40</gadget>
<output>251.2</output>

<result>251.2</result>