Someone noticed their $20 bill has a unique serial number which means it’s now worth $5,000

Someone’s $20 bill turned out to be worth up to 250-times more than he expected - and its all thanks to a detail most people would probably miss.

It was posted by a Redditor to the site’s ‘Interesting As F***’ section - and it didn’t disappoint.

The detail that made it so special? The serial number - which was simply the number ‘1’.

The person who posted it said they’d checked it out, and it could be worth around $5,000 to collectors.

“Note collectors will find that irresistible. Nice find. Keep it mint,” one person responded. It appears the person who posted it already has it protected in some kind of case.

“My 20 dollar bill with a serial number 1.”Photo courtesy of u/urshook1/Reddit

Others gave their insight into the rarity of a bill with a serial number one, but said that it’s not the only one.

“The letters before the numbers are the series run and there are dozens of series for each year they print them. Still exceptionally rare and makes it worth thousands, but it’s not the only 00000001,” wrote one.

Another added: “There are many bills with the number 1... the first two letters and the last letter determine the batch. That’s three combinations and idk the math but I’d imagine there are a decent number.”

While the eye-catching serial number is likely worth several thousand dollars, bills with errors and other mistakes on them are often worth more.

Check out some of the most expensive bills of all time, according to Ranker.com.

The $1,000 ‘Grand Watermelon’ Treasury Note ( 1890)

English: A Series 1890 $1,000 Treasury Note depicting George Meade with the signatures of William Starke Rosecrans and James N. Huston. Meade was a Major General (1862–69) in the U.S. Army (1835–69) and fought in the Mexican-American War and the American Civil War.National Numismatic Collection,National Museum of American History, Public domain, via Wikimedia Commons

In 2018, this bill was sold for $2 million.

It got its name due to the zeroes in “1,000,” favoring watermelons.

Only seven of these bills are known to exist, and General George Gordon Meade is on it.

$100 ‘Baby Watermelon’ Treasury Note (1890)

One hundred dollar bill series 1890 featuring David Farragut Federal government, Public domain, via Wikimedia Commons

Featuring U.S. Navy flag officer David Farragut is worth $10,000 to $200,000. This is the smaller version of the $1,000 Grand Watermelon bill.

It’s also reported that the copies of the bill that are lower grade have received up to $10,000.

Only 35 of these bills are around and available for private ownership.

Alexander Hamilton $1,000 Banknote(1918)

English:A Series 1918 $1,000 Federal Reserve Note. This serial #1 note was part of the U.S. Treasury collection transferred to the National Numismatic Collection at the Smithsonian Institution in 1978.Engraved signatures of Burke (Treasurer of the United States) and Glass (Secretary of the Treasury).National Numismatic Collection,National Museum of American History, Public domain, via Wikimedia Commons

The Alexander Hamilton $1,000 banknote has a starting price of $8,000. The 1918 series of $1,000 are “the highest denomination” and are still available for people to get their hands on.

$$5,000 and $10,000 bills can only be in museums now.