Even in this fast-paced digital world, I still make most of my purchases in cash.

I find keeping my wallet stocked with actual, paper money helps me track my spending.

Plus, I'm never out of luck when I go to a store or restaurant that only takes cash.

Of course bills have a downside too: they rip.

I've often had to tape together a $20 or $50 and make excuses to get a cashier to take it, so I was happy to learn that you can actually exchange damaged cash for its full value.

What can you do with a ripped bill?

The open secret about exchanging "mutilated" money was revealed this week by Daily Show writer Dan Amira.

Amira shared his experience being reimbursed for a ripped $10 bill.

"I don't know how it ripped in half," he wrote in a letter to the Bureau of Engraving and Printing.

"I just took it out of my pocket one day and it was in two pieces. I think it was just old."

Against all odds, the government actually sent Amira back a check for $10.

It wasn't just a gag by the TV writer, in fact anyone with damaged U.S. currency can send it in to be replaced.

But there are a few rules you must follow to get your money back.

The Mutilated Currency Division

Almost no one knows that the Treasury Department has an entire department for replacing damaged bills.

The bureau handles 30,000 claims a year, and hands out more than $30 million in replacement payments.

But there are a few conditions to get your money back:

• You must send in at least 50% of a bill to get a refund for it.
• If you have less than 50%, you must provide evidence that the missing portion of the bill was totally destroyed.

If you want to get some money replaced, follow the directions on the bureau's website.

Bear in mind they're constantly backlogged, so it can take up to 36 months to process your claim.

For best results, don't disturb any fragments of the bill. Pack them in cotton balls or plastic and ship them just as you found them (balled up, folded, etc).

The government will replace damaged coins too, but you have to process them through the mint.

It takes a lot to break a bill

The bureau says that the most common causes of damaged bills are rot from being buried underground, insect or rodent damage, dog damage, and fading caused by water or chemicals.

The average lifespan of a bill depends on the value. A $10 in high circulation will only last around four years, while $100s usually last 15 or more.

While you're looking out for old bills, be sure to keep your eyes peeled for rare coins.

Check your change for these valuables

Most people assume that rare and valuable coins are unusual and strange looking, but normally they blend right in with your change.

When Wisconsin's state quarter was printed in 2004, an extra leaf was included on the corn in some versions.

If you find a coin with this tiny mistake it could be worth up to $300 to you.

Likewise, there's a line of silver-colored aluminium pennies from 1974 that are worth a bundle today.

The U.S. mint was experimenting with different metals, and melted down most of the coins. The handful that were smuggled out of the mint are worth up to $250,000.

It's all in the details

One of the most famous mistakes is the "double ear" Lincoln penny, which adds an extra line behind the Great Emacipator's ear.

Spot one in the wild and it's easily worth a pretty penny - as in up to $250.

Another glaring error? The Kansas state quarter from 2005 was sometimes printed with the words "In God we rust."

Oops! That mistake's worth about $100.

Have you ever found a rare coin in your change?

[H/T: Mashable]