Place a largest circle in a square with a side length of 10m, what is the area of this circle in m**2.
边长是10m的正方形中放置一个最大的圆，这个圆的面积是多少m**2．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

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

<result>78.5</result>