If the radius of the small circle is a and the radius of the large circle is 2a, what fraction of the area of the small circle is the large circle?
如果小圆的半径是a，大圆的半径是2a，那么小圆的面积是大圆的几分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>