If it's a newer bill, look for the watermark. Which 20-Dollar Bill Serial Numbers Are Worth the Most? Serial numbers are a ...

Collectors love bills with low serial numbers, such as those below 1,000 or 100 (e.g., 00000100). On eBay, these kinds of bills can sell for anywhere from $10 to $300. The lower the serial number ...

The U.S. Federal Reserve has 12 banks, and each bank has a letter and number combination associated with it. On $5 bills and up, the bank identifier appears separately from the serial number ...