Divide a circle into several parts on average, and then put together an approximate rectangle, the circumference of which is increased by 8 cm. What is the area of this rectangle.
将一个圆平均分成若干份，再拼成一个近似的长方形，周长增加8厘米．问这个长方形的面积是多少．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">6.28 * 4</gadget>
<output>25.12</output>

<gadget id="calculator">25.12 / 2</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 + 4</gadget>
<output>16.56</output>

<gadget id="calculator">16.56 * 2</gadget>
<output>33.12</output>

<result>33.12</result>