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.