If the radius of a circle is 8 cm, what is the circumference of half the circle in cm?
一个圈的半径为8厘米，半个圆的周长为多少厘米．
<gadget id="calculator">3.14 * 8</gadget>
<output>25.12</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">25.12 + 16</gadget>
<output>41.12</output>

<result>41.12</result>