$100 Bill : In the world of currency collecting, errors are gold—sometimes literally. One recent example proved just how valuable a small printing mistake can be: a 2021 $100 bill with mismatched serial numbers has just sold for an astonishing $75,500 at auction.
What makes this six-figure note so valuable? It’s all in the details—specifically, the serial numbers, which are supposed to be identical on both sides of a U.S. banknote. When they aren’t, collectors take notice.
What Happened With This $100 Bill?
The rare $100 bill, printed in 2021, appears completely ordinary at first glance. But upon closer inspection, the serial numbers—printed in green ink on the front of the note—do not match. One corner displays a different number than the other, a mistake that’s only possible due to a rare printing misalignment.
This type of error, known as a mismatched serial number, is extremely uncommon. It occurs when the press that applies the serial numbers malfunctions or when a sheet misfeeds during the final printing stage. Since serial numbers are among the last elements added to a note, these errors are often caught before bills are released. But every now and then, one slips through—and when it does, collectors are ready to pounce.
Why It Sold for So Much
A mismatched serial number error already guarantees rarity, but the $75,500 price tag came down to a few key factors:
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Modern Date: A 2021 note with such an error is almost unheard of, making it especially rare.
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High Denomination: Errors on $100 bills are less commonly found than on smaller denominations.
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Excellent Condition: The bill was reportedly in uncirculated condition, which dramatically increases its value.
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Authentication: It was certified by a top grading service, confirming both its authenticity and the error.
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Strong Demand: Currency collectors and error specialists have driven up demand for high-grade modern mistakes in recent years.
This sale proves that even recent bills can be worth far more than their face value—if they carry the right kind of error.
What Is a Mismatched Serial Number?
On every U.S. bill, the two serial numbers printed on the front must be identical. A mismatched serial number error means one number differs from the other, usually by a digit or two. These mistakes are extremely rare, especially in modern currency, and highly prized by collectors.
Examples:
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One serial number might read MB12345678A
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The other might read MB12345679A
Even a single-digit mismatch can make a bill highly valuable—especially if it’s in mint condition and authenticated.
How To Spot a Rare Error Bill
If you’re wondering whether you might be holding onto a hidden gem, here are some things to look for:
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Compare Serial Numbers: Make sure they match exactly. A mismatch may be subtle.
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Check for Other Errors: Misaligned prints, missing elements, or upside-down seals can also be valuable.
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Inspect the Bill’s Condition: Uncirculated or crisp notes are far more desirable.
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Know the Series Year: Some series are more error-prone or sought-after.
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Get it Authenticated: Have any suspected error bill certified by services like PMG or PCGS Banknote.
Final Thoughts
A $100 bill’s face value may buy groceries—but if it has a printing error, it could buy you a new car, or even a small house. The recent $75,500 sale of a 2021 mismatched serial number note is a striking reminder of the hidden value that could be sitting in your wallet, purse, or piggy bank.
So before you spend your next Benjamin, take a closer look—you might be holding a fortune in plain sight.
Tip: Want to check your bills? Grab a magnifying glass, good lighting, and patience. Mistakes are rare, but the reward is real.