For some collectors, these fun sequences of numbers on a banknote are a step above ordinary notes.

An Ascending Pairs Serial Number is one where the first two digits are the same number and then each subsequent pair of numbers is one digit higher. For instance, the Culver City, California 1929 $5 National Bank Note below has an Ascending Pairs Serial Number of B001122A. (This PMG-certified note is part of a Heritage Auctions sale in February 2025.)

Descending Pairs Serial Numbers follow the same pattern except the digits grow smaller. This 2017A $1 Federal Reserve Note has a Descending Pairs Serial Number of K88776655A. (This note realized $150 in a Heritage Auctions sale in June 2021.)

Collectors and dealers with fancy serial numbers can submit them to PMG for certification and attribution under an applicable grading tier. All fancy serial number banknotes must be submitted on a separate submission form. There is no additional fee for this service.

To read the complete article, see:
The Fancy Serial Number Files: Ascending Pairs and Descending Pairs(https://www.pmgnotes.com/news/article/13704/fancy-serial-numbers-ascending-descending-pairs/)