Most of us handle $1 bills every day without a second thought. They’re crumpled into wallets, dropped into tip jars, or left forgotten in coat pockets. But some of these seemingly ordinary bills could actually be worth thousands of dollars — all because of their serial numbers.

Currency collectors and experts are particularly interested in bills with unique or rare serial numbers, often referred to as “fancy serial numbers.” These uncommon patterns are highly sought after, and their value can far exceed the face value of the bill, especially if the bill is in good condition.

Among the most valuable serial number types are low serial numbers, typically ranging from 00000001 to 00000100. Bills with repeating digits or patterns — like 12344321 or 88888888 — also catch collectors’ eyes. Another type, known as a “ladder” (such as 12345678), features numbers in perfect sequential order, making them extremely desirable.

“Radar” bills are another category, where the serial number reads the same forward and backward, such as 01133110. Collectors also look for “birthday” serial numbers, which appear to form a date, like 07041876 — possibly aligning with a significant historical or personal event.

“Star notes” are bills printed to replace damaged ones and are marked with a star (*) at the end of the serial number. These are relatively rare and can also be worth more than their face value depending on the serial number and condition.

The most coveted of all, however, is the “binary repeater” — a serial number made up of only two digits repeated in a distinct pattern, such as 01010101 or 29292929. These are exceptionally rare and, in top condition, can be valued at $5,000 or more. So next time you handle a $1 bill, check that serial number — it might be a hidden treasure.