Cut a rectangular cardboard with a length of 5 decimeters and a width of 4 decimeters into the largest square, then, what is the loss rate of this cardboard?
用长5分米、宽4分米的长方形硬纸板剪成一个最大的正方形，那么，这张硬纸板的损耗率是多少．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<gadget id="calculator">4 / 20</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(1/5) * 1</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>