The radius of a semicircle is 20 cm, what is the circumference of the semicircle?
一个半圆的半径是20cm，这个半圆的周长是多少厘米？
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">20 * 3.14 * 1</gadget>
<output>62.8</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">62.8 + 40</gadget>
<output>102.8</output>

<result>102.8</result>