How much money do people accidentally throw away every year?

Why do we lose money? It's probably for the same reason that we lose other important stuff, from cell phones to car keys. We're pretty absent-minded at times. A 2012 online study by a British insurance company, esure, concluded that the average person misplaces an average of 198,743 items over the course of a lifetime, and spends the equivalent of 230 days looking for them.

Stress, fatigue and multitasking all help to cause mental misfires that lead to us losing stuff, including money. Sometimes we fail to activate our hippocampus, the brain region that takes a snapshot of where we put that $20 bill from the ATM machine. Or else we fail to retrieve the reminder that our brain created. That forgetfulness may be genetic. Researchers have discovered that many people who are especially forgetful have a variation in the dopamine D2 receptor gene [source: Reddy].

But when it comes to small change, it may well be that we also just don't value it enough to hold onto it carefully. When you total up the pennies, nickels, dimes and quarters, it seems like a lot — cumulatively, there's about $15 billion in loose change in circulation [source: AmericaSavesWeek.org]. Coinstar, a company that operates coin-counting machines at supermarkets, says its customers estimate that they've got an average of $28 in coins in their pockets, on their nightstands or between couch cushions. But on average they cash in twice that, which tells you that they probably don't keep close track [source: Holland].

Thanks to inflation, a few pennies or nickels here and there don't seem to be worth much anymore — restaurants and convenience stores often have little trays of loose change at the counter, which they'll let customers use to pay an odd amount on a bill.

And when we accumulate change on our nightstands, banks aren't usually willing to just accept paper rolls of coins, as they once did. Coinstar charges a 10.9 percent fee to dispense paper bills for coins, though you could elect to accept a gift card to Starbucks, Amazon or other stores for free instead [source: Coinstar].

How people lose larger sums is a bit tougher to figure out, but we'll deal with that in the next section.

In an age when practically everyone seems to have a credit card and a lot of us make purchases and pay bills online, it might seem puzzling that anybody actually amasses enough physical cash to lose a sizable sum. One sign of the times: The Salvation Army reported in 2014 that contributions to its Christmas kettle program had fallen off 10 percent from between 2012 and 2014, which one official attributed to the fact that people carried fewer bills and coins in their wallets [source: Schmidt].

The truth is, though, that cash is far from dead. About 65 percent of Americans prefer to use it instead of plastic for purchases of $5 or less, according to a recent survey. And that preference gets stronger with age. While millennials are slightly more comfortable using credit or debit cards for small payments, 82 percent of people 65 and older prefer currency [source: Merzer]

Additionally, many of us don't completely trust the cashless economy — or, for that matter, banks. A 2015 American Express survey found that 29 percent of Americans are keeping at least some of their savings in paper money and coins, and a little more than half of those people have stashed the money in some secret location. According to another study, the most popular place to hide money is in the freezer (27 percent of cash hoarders), with another 20 percent using the sock drawer. A further 11 percent use the stereotypical mattress, and 10 percent prefer the cookie jar [source: Grant].

The problem, of course, is that people sometimes forget where they've stashed their savings. In 2013, a woman forgot that she'd stashed $98,000 in cash in a desk, and mistakenly sold it on Craigslist. Fortunately, she sold it to a rabbi, who found the money and returned every cent of it to her [source: Shaw]. On the other hand, in 2009, an Israeli woman replaced her mother's mattress, not knowing that $1 million was stashed inside. She searched three landfills but did not find that old mattress [source: Associated Press].