When inspecting a batch of products, the passing rate in the initial inspection is 96%. After re-inspection, 4 of the original unqualified products are qualified products. In this way, the passing rate of the products rises to 98%. How many products are there in this batch?
检验一批产品，初检时的合格率为96%经再次检验，原来不合格的产品中有4个是合格产品，这样产品的合格率上升到98%，则这批产品一共有多少个？
<gadget id="calculator">98 / 100</gadget>
<output>49/50 = around 0.98</output>

<gadget id="calculator">96 / 100</gadget>
<output>24/25 = around 0.96</output>

<gadget id="calculator">(49/50) - (24/25)</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">4 / (1/50)</gadget>
<output>200</output>

<result>200</result>