Here is a list of commonly collected fancy serial numbers.
Serial Number 1 through 9
Very simply these are the lowest of the low serials, and are the first numbers printed in any run: meaning 00000001 - 00000009. These notes are exceedingly rare.
Low Serial NumbersSerial numbers that start with four or more zeros are fancy: meaning 00000100 - 00009999. The more leading zeros, the better.
High Serial Numbers
Serial numbers that start with four or more nines are fancy: meaning 99990000 - 99999999. The higher, the better. All notes are printed starting with serial number 1, but recently notes have NOT been printed to 99999999. Notes printed on sheets of 32 and 50 within the past few decades (uncut sheets excluded) are only printed to 96000000. Prior to that, block letters have rolled over at various increments - 99200000, 99840000, and 99999999. This means that these super high serial numbers also tend to be older notes, which will skew their value higher.
For a recent note that has a block rollover at 96000000, you might think "that means 95999173 is rare because it's within 827 of the highest number, similar to five leading zeros." Maybe a collector might find it interesting to pay over face value for, but I think it would be considerably lower than a five leading zero number.
Stand Alone
A stand alone serial number contains one digit that is preceded and followed by all zeros. For example, 04000000 or 00008000.
Multi Millionaire / Trailing Zeros
A Multi Millionaire serial number contains a single digit number (1-9) that is followed by 7 zeros. For example, 10000000 thru 90000000. These numbers are very rare. Trailing zeros serial numbers that start with a 9 are more rare. This is because some currency blocks do not reach 90 million. So therefore, a serial number such as 90000000 will be more rare than a serial number such as 10000000.
Ladders
Each digit is one number higher or lower than the previous digit. Examples: 01234567, 98765432. Some people consider ladders fancy if they go up and down like: 23456765, or wrap around from zero: 56789012. Their rarity is likely why the definition of a ladder serial number was expanded to include other, more common types.
True Ladder
A true ladder serial number contains the ascending digits 1-8. It's the number 12345678. These serial numbers are incredibly rare.
Reverse Ladder
A reverse ladder serial number, also known as a stepdown or backwards ladder, contains the descending digits 8-1. It's the number 87654321. These serial numbers are incredibly rare.
Broken Ladder
A broken ladder serial number contains ascending digits, but not the digits 1-8. The digits will appear "broken" with the number 0 before, after, or in-between the other digits. Examples include: 01203004 and 40506078. Broken ladder serial number bills are moderately rare.
8 Digit Broken Ladder / Scrambled Ladder
A scrambled serial number contains eight unique digits. The digits are not sequential. Examples include: 13254678 and 61532478. Scrambled ladder serial number bills are moderately rare
4 Digit Ladder
A 4 Digit Ladder serial number contains the ascending or descending digits in the serial. Examples include: 012346957 or 27987621
4 Digit Double Ladder
A 4 Digit Ladder serial number contains four ascending or descending pairs in the serial. Examples include: 11223344, or 99887766
5 Digit Ladder
A 5 Digit Ladder serial number contains the ascending or descending digits in the serial. Examples include: 01234595 or 20987621
6 Digit Ladder
A 6 Digit Ladder serial number contains the ascending or descending digits in the serial. Examples include: 12345678, 92345674 or 27987654
7 Digit Ladder
A 7 Digit Ladder serial number contains the ascending or descending digits in the serial. Examples include: 12345678, or 23456789
Binary
Binary serial numbers contain only two unique digits (order doesn't matter). Example: 74774774.
True Binary
True Binary serial numbers contain only zeros and ones - like machine code. Example: 01010101
Trinary
Trinary serial numbers are like binaries, except that they contain only three unique digits. Again, order doesn't matter. Example: 79557977
True Trinary
True Trinary serial numbers contain only zeros, ones, and twos. 01201201
Quadinary
Quadinary serial numbers are like binaries, except that they contain only four unique digits. Again, order doesn't matter. Example: 12341432 or 48678467
True Quadinary
True Quadinary serial numbers contain only zeros, ones, twos, and threes. 01233201
Repeater
The first half and second half of the serial number are the same. Examples: 74627462
Super Repeater
A super repeater is when the first two digits are repeated four times. Example: 39393939.
Quad Double
A quad double serial number contains four sets of double digit pairs. For example, 11442288. These numbers are moderately rare.
Double Quad (Binary)
A double quad serial number has the same first four digits and the same last four digits. For example, 55554444 or 77771111. Double quad serial number bills are rare.
Radars
True Radar
Radar serial numbers are also known as a palindrome serial numbers, reads the same forward as it is backwards. It is named this because the word "r-a-d-a-r" is spelled the same forward and back. Examples: 12533521, 49366394.
Super Radar
Super radars serial numbers have the same first and last digit with six of the same digit in between. For example, 84444448.
Repeater Radar
The radar is also a repeater, meaning the first four digits and last four digits are the same as well as the entire number being the same forwards and backwards. These types of radars are inherently also binary. Examples: 34433443, 61166116
Binary Radar
The radar only consists of two digits. Examples: 83833838
Radar-Repeater-Rotator
The Radar-Repeater-Rotator is read the same left to right, contains a three digit repeater and can be read the same right side up and upside down. Examples: 808808.
Rotator / Flipper
A serial number that doesn?t change if read upside down. The only numbers that can be rotated are: 0s, 1s, 6s, 8s, and 9s.
Pairs
3 Consecutive Pair Doubles
A Consecutive Pairs serial number that has 3 Consecutive Pairs. For example, 56677884 or 11335571.
4 Consecutive Pair Doubles
A Consecutive Pairs serial number that has 4 Consecutive Pairs. For example, 55667788 or 11335577.
Pairs / Doubles
Doubles occur when a serial number includes pairs of numbers, such as 12264795. There are other types of doubles, such as a serial number that contains two or three sets of pairs - 12235889, 22867799.
4 Pairs
A 4 Pairs serial number has 4 Pairs. For example, 56677885 or 71133557.
In-A-Row
5-In-A-Row
Five of the same digit are in a row. Example: 55555678, 15555578, 12555558, or 12355555.
6-In-A-Row
Five of the same digit are in a row. Example: 66666678, 12666666, or 16666668
7-In-A-RowSeven of the same digit are in a row. Example: 77777771, 17777777
8-In-A-Row / 8-Of-A-Kind / Solid
Every digit in the number is the same. Examples: 11111111, thru 88888888
Of-A-Kind
3-Of A-Kind / Angel Numbers
4-Of-A-Kind / Solid Quad
Four digits in the number is the same in a block. Examples: 11113597, 96178888. or 15999976
Double 4-Of-A-Kind (Binary)
Four digits in the number is the same in a block. Examples: 11131333, 110000011, 12112211. or 15999976
5-Of-A-KindSimilar to 5-in-a-row. Example: 55556785, 15557855, 12558555, or 55551235
6-Of-A-Kind
Similar to 6-in-a-row. Example: 62366666, 66346666, 66646668, 66665676, or 66666678
7-Of-A-Kind / Near Solid
Similar to 7-in-a-row except that the lone digit is somewhere in the middle of the number. Example: 77177777
8-Of-A-Kind / 8-In-A-Row / Solid
Every digit in the number is the same. Examples: 11111111, thru 88888888
Bookend
A bookend serial number contains the same two or three digits at the beginning and at the end. For example, 42451424 or 71843071.
Date/Birthday
Serial numbers can contain dates. The format might change depending on your locale, but a number like 07041776 or 02221732 could indicate the finalization of the Declaration of Independence, or George Washington's birthday. Some people try to collect numbers matching their birthdays or other life milestones.