Divide a circle into 64 equal parts and form an approximate rectangle. If the measured length of this rectangle is 6.28 decimeters, what is the area of the original circle in square decimeters?
将一个圆平均分成64等份后拼成一个近似的长方形．如果测得这个长方形的长为6.28分米，那么原来的圆面积是多少平方分米．
<gadget id="calculator">3.14 * 2 * 2</gadget>
<output>12.56</output>

<result>12.56</result>