The diameter of a semicircular flower bed measured on a drawing with a scale of 1:300 is 4 cm, find the perimeter of the flower bed.
在一幅比例尺是1：300的图纸上测得一个半圆形花坛的直径是4厘米，求这个花坛的周长．
<gadget id="calculator">1 / 300</gadget>
<output>1/300 = around 0.003333</output>

<gadget id="calculator">4 / (1/300) / 100 / 2</gadget>
<output>6</output>

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

<gadget id="calculator">4 / (1/300) / 100</gadget>
<output>12</output>

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

<result>30.84</result>