Change the wire ring with a radius of 5cm into a square wire ring. Compared with the ring, the area of the square wire ring is reduced by how many cm**2.
把半径为5cm的铁丝圆环改成一个正方形的铁丝圈，这时正方形铁丝圈与圆环相比，面积缩小了多少cm**2．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<gadget id="calculator">31.4 / 4</gadget>
<output>7.85</output>

<gadget id="calculator">7.85 * 7.85</gadget>
<output>61.6225</output>

<gadget id="calculator">78.5 - 61.6225</gadget>
<output>16.8775</output>

<result>16.8775</result>