The circumference of a semicircle is 15.42, what is the circumference of the whole circle in centimeters?
一个半圆的周长是15.42，整个圆的周长是多少厘米．
<gadget id="calculator">3.14 + 2</gadget>
<output>5.14</output>

<gadget id="calculator">15.42 / 5.14</gadget>
<output>3</output>

<gadget id="calculator">3.14 * 3 * 2</gadget>
<output>18.84</output>

<result>18.84</result>