Many collectors specialize in collecting banknotes with unusual serial numbers. Some banknotes with sought after numbers can be worth a lot more than those with random numbers.
Examples of fancy numbers are:
If all the digits in the serial number are the same, it is called a solid note. Solid notes are extremely rare. Examples are 00000000, 55555555, 44444444, and 88888888.
Serial number 00000000 is usually reserved for specimen notes
Eight (8) is considered the most lucky number for the Chinese people around the world. The word “eight” in Chinese sounds similar to the word meaning “prosperity”. So notes with solid number 88888888 are highly in demand. Four (4), on the other hand, is a number to avoid because it sounds similar to the word meaning “death”.
The lower the serial number, the more valuable is the note. A serial number of 00000001 is very hard to get. Actually, any number under 1000 is desirable.
A serial number that reads the same forwards and backwards is a radar note. For example, number 54344345 is a radar serial number because you can reverse the digits and it will still be the same number.
A note with a serial number containing just two unique digits is a binary note. An example is number 7575757. If all the digits consist of only 0s and 1s, then it’s a true binary. An example is number 01110011.
When a serial number contains pairs of numbers, it’s a doubles note. An example of a doubles is 11993355.
Serial numbers with a sequence of numbers that repeats itself is a repeater. Serial number 11221122 is examples of repeaters.
You can have various combinations of the above three categories.
Binary Repeater: 10101010
Doubles Repeater: 33663366
Binary Doubles Repeater: 11001100
Consecutive notes are two or more separate notes with consecutive serial numbers. You have two consecutive notes if one has a serial number 063348 and the other 3063349.
A bookend note has a serial number having the same sequence of digits at both ends. An example is serial number 20516320. “20” is the sequence of digits appearing at both the beginning and end of the serial number.
When a serial number with digits either in ascending or descending numerical sequence, it’s a ladder note. An example of ladder note is serial number 23455432 which also happens to be a radar note.
If a serial number contains a sequence of digits representing the year of one's birthday, then it's a birthday note. For example, suppose you were born on November 15, 1953, 11151953 would be your birthday banknote.
Since birthday serial number is of interest only to you, it’s probably more affordable if you can find one.