There are two circles, big and small. The circumference of the big circle is 314m, and the radius of the small circle is (2/5) of the radius of the big circle. What is the area of the small circle?
有大小两个圆，大圆的周长是314m，小圆的半径是大圆半径的(2/5)，小圆的面积是多少？
<gadget id="calculator">314 / 3.14 / 2</gadget>
<output>50</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">50 * (2/5)</gadget>
<output>20</output>

<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">3.14 * 400</gadget>
<output>1_256</output>

<result>1_256</result>