The diameter of the circle is reduced to the original (1/10), and the area is reduced to the original amount.
圆的直径缩小为原来的(1/10)，面积缩小为原来的多少．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) ** 2</gadget>
<output>1/100 = around 0.01</output>

<result>1/100 = around 0.01</result>