The circumference of the circle is reduced to the original (1/2), and the area of the circle is reduced to the original amount.
圆的周长缩小到原来的(1/2)，圆的面积缩小到原来的多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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