After using 20% of 100 sheets of paper, and using the remaining 20%, how many sheets are left
100张纸用20%后，又用了余下的20%，还剩多少张
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">100 * (4/5) * (4/5)</gadget>
<output>64</output>

<result>64</result>