If a square log with a side length of 20 cm and a length of 1 meter is processed into the largest cylinder with the same height, how much wood should be removed?
把一横截面是边长是20厘米的正方形、长是1米的方木，加工成同样高的最大圆柱，要去掉多少木料？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) * (1/5) * 1</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/5) / 2</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">3.14 * (1/100) * 1</gadget>
<output>0.0314</output>

<gadget id="calculator">(1/25) - 0.0314</gadget>
<output>0.0086</output>

<result>0.0086</result>