What is the circumference of a semicircle with a radius of 2 meters
一个半径为2米的半圆，它的周长是多少米
<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

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

<gadget id="calculator">6.28 + 4</gadget>
<output>10.28</output>

<result>10.28</result>