With so many different kinds of collectors in the world, perhaps it shouldn’t be surprising that some people like to collect dollar bills.

The stranger—or more rare—the serial number is, the more attractive it is to potential collectors. However, this means that many people are walking around with these rare dollar bills in their pocket—and they don’t even know it! Now, if you’re chomping at the bit to find out if your petty cash may make you rich, it’s time to go to http://coolserialnumbers.com.

On this site, you’ll be able to check your numbers and see if they’re the ones that collectors are actively seeking. Download the want list and keep an eye on your change in the future; you never know when just one dollar bill can make all of the difference in the world! Although some of their most-wanted items may seem random, there are some patterns involved in all of this. For instance, collectors really like when there are seven in a row of the same number.

Double quads, super radars, repeaters and binaries are more examples of serial numbers that are in hot demand right now. If you want to make some money without lifting a finger, open up that wallet and see what kind of magic you might be able to find.

 

Some of your one dollar bills could be worth a whole lot more. Bills with unique serial numbers are going for thousands of dollars on the website Cool Serial Numbers.

One of the most sought after bills right now is the $1 bill with a serial number that’s made up of seven zeroes and the number two. It’s going for $2,500.