If the radius of the base of a cone is increased by 25%, the height must be decreased to keep the volume constant.
把一个圆锥的底面半径增加25%，要使体积不变，则高要减少多少．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) ** 2</gadget>
<output>25/16 = around 1.5625</output>

<gadget id="calculator">1 / (25/16)</gadget>
<output>16/25 = around 0.64</output>

<gadget id="calculator">1 - (16/25)</gadget>
<output>9/25 = around 0.36</output>

<result>9/25 = around 0.36</result>