Cut out the largest semicircle on a piece of square paper with a side length of 8 cm. What is the circumference of this semicircle in cm?
在一张边长是8cm的正方形纸上剪下一个最大的半圆，这个半圆的周长是多少cm．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 + 8</gadget>
<output>20.56</output>

<result>20.56</result>