Divide a circle into several equal parts along the radius, and cut them together to form an approximate rectangle. It is known that the width of this rectangle is 6 centimeters, and what is the length in centimeters.
把一个圆沿着半径平均分成若干等份，剪拼成一个近似的长方形，已知这个长方形的宽是6厘米，长是多少厘米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

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

<result>18.84</result>