Very little is as awesome as holding the winning number in your hot little hands, whether you’ve purchased the fateful lottery ticket or your number was just called at the deli. (Wait, am I the only person who gets excited by that? What can I say? I like to celebrate the small wins.)

However, you may be sitting on a winning number of another kind without even realizing it. What am I talking about?

Check Your Dollar Bills

Specifically, dollar bills with strange serial numbers — ones that aren’t easy to come by.

Turns out antique coins aren’t the only currency worth cash to collectors.

Here’s a rundown of the sort of serial numbers these collectors are looking for:

Seven repeating digits in a row on $1 Federal Reserve notes (i.e., 09999999, 77777776)

Seven of a kind on $1 Federal Reserve notes (i.e., 00010000, 99999099)

Super repeaters on $1 Federal Reserve notes (i.e., 67676767)

Double quads on $1 Federal Reserve notes (i.e., 00009999)

Can You Really Get Rich With Dollar Bills?

Just ask these collectors and experts, who estimate specific “hot” serial numbers to be worth big bucks:

The Boston Globe reported in 2013 that one particularly patriotic collector was interested in bills with the serial number 07041776 in honor of the date of the signing of the Declaration of Independence. He was said to be willing to pay $500 to $1,000 for $2 bills with this serial number. (Why $2 bills? Each one portrays the historic event.)

In the U.K., an eBay seller reportedly made 7,100 pounds from the sale of a single 20p coin.

When the redesigned $100 bill was released in October 2013, Dustin Johnston, director of Heritage Auctions in Dallas, told The Boston Globe the very first bill (serial number 00000001) could be worth a whopping $10,000 to $15,000.

Go ahead: Take a few minutes to check your wallet, pockets and maybe those couch cushions. If you think you’ve got a serial number collectors will be interested in, here’s what to do next.

Show Them the Money

Depending on the rarity of your bill’s serial number, it could be worth a crazy amount of money — when we checked eBay on Sept. 27, 2017, we found dollar bills with fancy serial numbers listed for as much as $550.

And be sure to tell your grandma you want your birthday $20 in singles this year. Because, as the New York Lottery says, “Hey, you never know.”