How Well Do You Know Your Money?

We spend so much time worrying about money, where it’s coming from, how much things cost and whether we can afford the things we need, much less want, we don’t always stop to consider that money is, inherently, interesting. We took a closer look at money facts that might make you gasp, laugh and shake your head.

There Was Once a $10,000 Bill

If you thought a $100 bill was impressive, imagine whipping out a $10,000 bill when you go shopping. Actually you’d probably not whip that much money out at all, only depositing it as fast as you could into a bank account. Though the Federal Reserve stopped printing these bills (along with $500, $1,000 and $5,000 bills) in 1945, they remained in circulation until 1969, said Scott Alan Turner, CFP, a financial planner and consumer advocate at Rock Star Financial. Finding one today would be rare indeed.

The Million-Dollar Penny

When is a penny worth more than one cent? Well, it actually costs about 1.7 cents to make a penny, according to the U.S. Mint, so they’re not really worth the effort of making them. Additionally, according to Turner, “The most valuable penny ever sold went for $1.7 million. Its value was because of a printing error that occurred in 1943.”

Salt Was Once a Form of Currency

That salt shaker on your table isn’t worth very much now, but ancient cultures used salt as a form of money, said Asher Rogovy, CIO of Magnifina, and an SEC-registered investment advisor. “At the time, salt was highly valued for its ability to preserve food. Salt also has the crucial feature of being easy to divide. Etymologists connect the word ‘salary’ to European root words for salt, such as ‘sal’ or ‘sel.’ It is also thought that salt’s history as a currency led to the expression ‘to be worth one’s salt.'”

There’s No Paper in Your Money

Your “paper” dollar bills are not actually made of the same tree-based cellulose that most paper derives from, according to Matt Campbell, CFO at Budgetable and a certified financial planner, and verified by The U.S. Bureau of Printing and Engraving. “Paper money isn’t paper, it’s 75% cotton and 25% linen.” So unique is the feel of the “paper” dollars are made from, well-trained people can detect a counterfeit bill simply by how it feels, according to How Stuff Works.

Counterfeiters’ Secret Trick

Campbell also pointed out that one way counterfeiters trick law enforcement is to make their fake bills a little less than perfect, as “too perfect” bills are often a giveaway. However, the U.S. Treasury has made U.S. currency hard to counterfeit, with a number of special features that require sophisticated technology to reproduce, including color shifting ink, a security thread woven into the bill, a special watermark and microprinting so small it requires a magnifying lens to see it.

What the Secret Service Has To Do With Money

Most people associate the Secret Service with protecting the president of the United States, but it was actually created first to tackle counterfeiting, said Mathias Ahlgren, founder and owner of Website Rating.

“According to The United States Secret Service, one-third to one-half of all money circulating in the U.S. [after World War I] was counterfeit. It was not until 1901, after President William McKinley was assassinated, that The Secret Service also started protecting The President of The United States.”

Don’t Throw Away Your Damaged Dollars

Damaged money can still be worth something, according to Ernests Embutnieks, CEO and founder at perfectgift4. “Don’t toss damaged cash just because it’s been damaged significantly. The Department of Engraving and Printing may be able to buy it back for its full worth.” To do so, all security features must be intact in order to be eligible for a note’s full redemption, he said. “If you have less than half of the note but can show how it was damaged and how the missing pieces were destroyed, you may be eligible.”

Depression Era Currency

“In the depths of the Great Depression, many cities and counties started issuing their own currency, known as scrip, to make up for the lack of available dollars and keep their local economies going,” said Carter Seuthe, CEO of Credit Summit Payday Loan Consolidation. This scrip was usually printed on cheap paper, but some localities used scraps of metal, wooden coins or even seashells for this purpose.

Pennies in Your Garden Deter Pests

Pennies, perhaps the most useless form of coin currency, can be more useful as a natural pest deterrent in your garden. According to Adam Ng, CEO and founder of Trusted, “Pennies buried in a garden will repel slugs, which get electric shocks from touching copper and zinc.” HGTV offers a tutorial for making a “penny ball.”

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This article originally appeared on GOBankingRates.com- It’s National Trivia Day: How Well Do You Know Your Money?