If the radius of a semicircle is 6 decimeters, what is its circumference?
一个半圆的半径是6分米，它的周长是多少分米．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 6 * 1</gadget>
<output>18.84</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">18.84 + 12</gadget>
<output>30.84</output>

<result>30.84</result>