If the circumference of the circle is reduced to the original (1/2), what is the area of the circle?
圆的周长缩小为原来的(1/2)，那么圆的面积变为原来的多少
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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