Master Li produced a total of 180 parts, with a pass rate of 90%. How many of them are unqualified?
李师傅一共生产了180个零件，合格率是90%，其中不合格的零件有多少个？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">180 * (1/10)</gadget>
<output>18</output>

<result>18</result>