If the circumference of a circle shrinks to 75% of its original size, how much does its area decrease?
一个圆的周长缩小到原来的75%，则它的面积减少了多少．
<gadget id="calculator">7 / 16</gadget>
<output>7/16 = around 0.4375</output>

<result>7/16 = around 0.4375</result>