Dongfeng Light Bulb Factory produces a new type of energy-saving light bulb. The first batch of 4,000 units is produced, with a pass rate of 98%. How many unqualified light bulbs are there?
东风灯泡厂生产一种新型节能灯泡，首批共生产4000个，合格率为98%，不合格灯泡有多少个？
<gadget id="calculator">98 / 100</gadget>
<output>49/50 = around 0.98</output>

<gadget id="calculator">1 - (49/50)</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">4_000 * (1/50)</gadget>
<output>80</output>

<result>80</result>