What is the circumference of a semicircle with a radius of 3 cm?
一个半径为3cm的半圆，周长是多少cm
<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">9.42 + 6</gadget>
<output>15.42</output>

<result>15.42</result>