A square is surrounded by a piece of wire with a circumference of 25.12 cm. What is the area of a circle surrounded by this piece of wire?
用一段铁丝围成一个正方形，周长25.12厘米，用这段铁丝围成一个圆面积是多少．
<gadget id="calculator">25.12 / 3.14 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>