At first glance, this riddle feels way more complicated than it actually is.
People start throwing around answers like $170 or even $200, and somehow everybody becomes convinced they’re right. But the trick here is not really about math. It’s about following the money carefully instead of overthinking the situation.
Here’s the setup.
A thief steals $100 from a store register. Later on, the same thief returns to the store and uses that exact $100 bill to buy $70 worth of merchandise. The cashier gives him $30 in change without realizing the money was stolen earlier.
So the big question is simple:
How much money did the store actually lose?
A surprising number of people answer this incorrectly because they mentally separate the theft from the purchase. But the moment you track the same hundred dollar bill from start to finish, the answer becomes much clearer.
The total loss is exactly $100.
That’s it.
The confusion happens because people accidentally count the stolen bill twice.
Let’s slow it down a little.
At the beginning, the store has all its inventory and all its cash. Then the thief steals $100 from the register. At that moment, the store is down by $100.
Pretty straightforward so far.
Now comes the part that trips everyone up.
The thief walks back into the store and buys $70 worth of products using the same stolen hundred dollar bill. The cashier accepts it as normal payment and gives back $30 in change.
What does the thief leave with?
He leaves with:
$70 worth of merchandise
Plus $30 cash in change
That equals $100 total.
Meanwhile, the original stolen $100 bill is now back inside the cash register. The store recovered that money the moment the fake “purchase” happened.
So in the end, the only real loss is:
$70 in products
$30 in cash
Total loss = $100
A lot of people mistakenly think the store lost the original stolen money plus the merchandise, but that doesn’t make sense because the same bill returned to the register. You cannot count it twice.
Honestly, this puzzle says more about how the brain works than it does about arithmetic. Once people hear the explanation, most either laugh immediately or sit there annoyed wondering how they missed something so obvious.
The wording creates the illusion of extra complexity. Our brains hear “robbery” and “purchase” and automatically split them into separate events even though they’re connected by the exact same money.
Another easy way to picture it is this:
Imagine the thief simply walked into the store and somehow left with $70 worth of goods and $30 cash. Without all the extra story details, everybody would instantly agree the loss was $100.
That whole stolen bill coming back into the register is basically just distraction.
And that’s why this little riddle keeps starting arguments online. People trust their first instinct too quickly instead of following the actual flow of money.
In the end though, no matter how many ways people try to calculate it, the answer never changes.
The store lost exactly $100.