A "big yellow croaker" during the Republic of China is roughly equivalent to how many RMB today. It is difficult to determine an accurate answer to this question. Because the value of currency changes over time and is also affected by other factors such as inflation and market supply and demand.

However, we can estimate it through some reference data. According to historical records, a "big yellow croaker" during the Republic of China was worth tens to hundreds of cash. According to the exchange rate at the time, 1 Wen was equivalent to 1 cent. Therefore, it can be roughly estimated that the current value of a "big yellow croaker" may be between tens to hundreds of RMB.

Please note that this is only an estimate and actual values ??may vary. If you want a more accurate answer, it is recommended to consult a professional historian or economist.