piece of rectangular paper with a length of 25 cm and a width of 20 cm, cut out the largest circle on this paper, what is the remaining area after the circle is cut out?
一张长方形的纸，长25厘米，宽20厘米，在这张纸上剪一个最大的圆，圆剪下后，剩下的面积是多少？
<gadget id="calculator">25 * 20</gadget>
<output>500</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">500 - 314</gadget>
<output>186</output>

<result>186</result>