What is the circumference of a semicircle with a diameter of 8 cm in cm?
一个直径8cm的半圆，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>