Xiaojun wants to use an iron wire to form a semicircle with a diameter of 8 cm. How long is the iron wire?
小军要用一根铁丝围成一个直径是8厘米的半圆面，需要多长的铁丝？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 + 8</gadget>
<output>20.56</output>

<result>20.56</result>