Serial numbers are one of the oldest tracking and security devices used on banknotes. They can vary from only a few numbers to a long string of numbers and letters, and some even have three distinct serial numbers. To those who know their methods, the serial numbers can divulge several things such as the year it was issued, the place it was made, if it was part of a collectors only series (like un-cut sheets of banknotes), if it was a replacement for a defective banknote and more.
One obvious use for serial numbers is the ability to track the note. There are web-sites that are devoted to tracking where and when banknotes have been sent. You can see where certain notes have traveled and what was purchased with them – No, this isn’t Big Brother keeping an eye on us, but rather just fun sites like www.WheresGeorge.com for USA banknotes and www.WheresWilly.com for Canadian banknotes. These sites can be fun to watch where people take the money you briefly held in your hand. But after they are delivered to banks from the issuing authority, there usually isn’t a large demand for tracking banknotes outside of certain law enforcement activities.
Serial numbers can be used as a security measure as well. Counterfeit notes have been known to use a limited number of serial numbers for their purposes, and they can sometimes be flagged or verified by the serial numbers. Serial numbers can seem as a string of meaningless numbers to most of us, but some issuing authorities throw in a prefix, suffix or a specific numbering method to denote what values of banknotes it should be, or the year of issue. So if you counterfeit such a banknote, you need to make certain that the serial number is one that matches the design of banknote issued, as some banknotes designs change rapidly.
There are certain serial numbers known as Replacements. They are assigned to banknotes that are found to be defective or have been destroyed. They are generally denoted by either a prefix or suffix such as ZZ 12345678 or 12345678 /Z. Quite a lot of nations use a star for this purpose, so it would be something like 12345678¶. To the collector, these notes generally bring a premium to the cost of a collectible note.
There are serial numbers that are considered to be ‘Fancy’ numbers as well. These notes can carry a premium depending on the type of ‘Fancy’ number. The numbers are generally made up of certain numbers that have special meanings to them. Such numbers can be ‘Ladders’: 12345678, ‘Solids’: 55555555, ‘Repeater’: 24852485, ‘Radar’: 74122147, etc. There are other types as well, such as birthday formats like MMDDYYYY or 02121809 for February 12th, 1809. Such a number sequence on a US Five dollar banknote would fetch a great premium as it is Lincoln’s Birthday.
There are some banknotes known as Specimen banknotes and these mostly use all zeroes in them. Specimen notes are used by issuing authorities to familiarize law enforcement, bank personnel, and others to new issues of banknotes, and should carry an over-stamp on them stating they are Specimen banknotes.
There are certain banknotes that have no serial numbers. Such notes are generally low value notes, but not always. One nice example is the Canadian 1 Dollar banknote from 1967. While there were banknotes issued this year with serial numbers on them there were a large number issued with a commemorative Centennial date of 1867-1967 instead. But others such as the Hong Kong 1, 5 and 10 cent banknotes had no serial number on them.
Then there are the serial numbers with errors. Most errors are mismatched sets of numbers such as the left side of the banknote having 25845612 and the right side of the note having 25845613. These notes will also carry a premium over other normal notes in the same condition.