After testing a batch of parts, it is found that there are 4 unqualified parts. To make the qualified rate reach 98%, how many qualified parts must be produced.
一批零件经检测，发现有4个不合格，要使合格率达到98%，必须要生产多少个合格零件．
<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 / (1/50)</gadget>
<output>200</output>

<gadget id="calculator">200 - 4</gadget>
<output>196</output>

<result>196</result>