The radius of a circle is 4 cm, what is the circumference of a semicircle equal to the radius of this circle?
一个圆的半径是4厘米，和这个圆半径相等的半圆的周长是多少厘米
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 * 3.14 * 2</gadget>
<output>12.56</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

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

<result>20.56</result>