Produce a batch of parts, a total of 500, 10 unqualified, what is the pass rate
生产一批零件，共500个，10个不合格，合格率是多少
<gadget id="calculator">500 - 10</gadget>
<output>490</output>

<gadget id="calculator">490 / 500</gadget>
<output>49/50 = around 0.98</output>

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

<gadget id="calculator">(49/50) * 1</gadget>
<output>49/50 = around 0.98</output>

<result>49/50 = around 0.98</result>