WASHINGTON D.C. (WVNS) – Have you ever wondered why some U.S. dollar bills have a star at the beginning or end of their serial number? The answer can net someone a lot more money than just a $1 bill would ever be worth.

All United States bills have either a 10 or 11-digit serial number in order to make each bill unique. Ten-digit serial numbers were on all bills until 1996. The 1996 bills (and all produced since then) have an 11-digit serial. The serial number consists of the following:

  • The first letter, only found on the new-style bills, represents the series of the bill. The series indicates the year in which the design of the bill was approved for production. This begins with A, and moves through the alphabet each time a new series is needed (for example, each time there is a new secretary of the treasury, the bill design changes because the secretary’s signature is on all currency). You can also find the series of the bill printed directly to the bottom-right of the portrait.
  • The second letter (or first, if you’re looking at an old-style bill) represents the district of the Federal Reserve Bank that your bill was issued from. As there are 12 Federal Reserve Banks, this letter can range from A to L, with A representing Boston and L representing San Francisco.
  • The eight digits that follow represent a unique ID number. This number increases sequentially as each bill is printed. Using these digits alone, there would be a possible 99,999,999 bills issued per bank.
  • The final letter is used to raise the number of possible bills beyond 99,999,999. Altogether, there are a possible 2,499,999,975 serial numbers for each and every bank.

Sometimes, a bill shows up that has a small star in place of the first or final letter in the serial.

This star is printed on what are knwon as replacement notes. When a printing error renders a set of bills unusable during a print run, replacement notes are printed to be used in place of the old bills. With replacements notes, a set of serial numbers can still have the proper number of bills even if the original bills had to be pulled.

The replacement notes have their own sequence, using the star as their final “letter.” This allows for 99,999,999 possible replacement notes for any given bank, series and denomination. According to the Paper Money Collecting FAQ, this should be more than enough: there’s only about one error in every 100,000 U.S. bills.

Replacement notes aren’t usually worth more than regular bills. If a replacement note has a particularly interesting serial number — like 00000001 or 999999999 — that’s when it can be worth more. If you own a large number of consecutively numbered replacement notes that you keep together as a lot, they could be sold to the highest bidder as a collector’s item.

You can check out your star note’s rarity if you have one right here.