The diameter of a semicircle is 20 cm, what is its circumference in cm
一个半圆的直径是20厘米，它的周长是多少厘米
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">3.14 * 10</gadget>
<output>31.4</output>

<gadget id="calculator">31.4 + 20</gadget>
<output>51.4</output>

<result>51.4</result>