When the radius of the circle is reduced to its (1/3), the area is reduced to the original area.
圆的半径缩小到它的(1/3)时，面积就缩小到原面积的多少．
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<result>1/9 = around 0.111111</result>