JOPLIN, Mo. (KSNF) — That $1, $5, or $10 bill in your wallet might be worth way more than its face value.

Knowing what your paper money might be worth is all in the serial number. Serial numbers are eight digits long and are unique to each bill. They are paired with other identifying letters and numbers that identify the series year the bill is from and where it was printed. Serial numbers are found on the front of U.S. currency and are always printed twice.

One of the most valuable serial number variations is known as a “ladder,” and could be worth anywhere from $9 to $100,000, according to financial news outlet The Penny Hoarder. When the serial number ascends (example: 12345678) or descends (example: 8765431) in order, currency collectors/dealers call it a ladder.

Eric Gerner, owner of Gold and Silver of Joplin, LLC., said the worth of a modern bill depends on its serial number and how unusual it is. Gerner said currency collectors look for several different types of fancy serial numbers that stand out from the crowd.

“There’s a whole family of collectors notes when it comes to looking at the serial number. You can look for repeater notes, and what I mean by that is eight digits that repeat, such as 08080808. There’s also three and four number repeaters. Of course, you have your ladders that go both up and down. There’s what we call bookends, where you have the first four numbers that match. I can go on and on,” said Gerner.

Check your $2 bills — they could be worth thousands

There are several ways to determine if the arrangement of the serial numbers on a particular bank note might fetch you some extra cash. One way is by going to a website such as Fancy Serial Number Checker, and typing in the eight-digit sequence of numbers. The website will determine how “fancy” or rare your bank note is and provide a resource to determine the approximate worth.

Another way to determine the value of U.S. paper money based on the serial number is to have it examined by a reputable currency dealer/collector.

“If you have a question about the worth of collectable currency, have it looked at by a professional. Having it looked at by someone who’s been in the business as long as I have is always a good idea. That’s the best way to ensure the currency you have is authentic. I tell people every day, ‘You don’t have to sell your stuff when you bringing it here.’ We’re here to provide information and to help educate the public,” said Gerner.

Many Buffalo Nickels worth more than five cents

For those who are new to currency collecting, Gerner says a great place to start is with your own wallet — by glancing at the serial numbers printed on each bill.

“One thing you have to remember with currency collecting — whatever serial number you find that you like, whether it’s a birthday note, or a repeater, or a ladder, or whatever — you need to understand that you’re holding the only one that’s available,” said Gerner. “The only one that exists.”