If the diameter of a circle increases from 2 cm to 6 cm, how much does its circumference increase in cm?
一个圆的直径从2厘米增加到6厘米，它的周长增加了多少厘米
<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<result>25.12</result>