At first glance, this seems like an easy math problem, and most people are confident they know the answer within seconds. But once they start thinking about it, the puzzle becomes surprisingly confusing. Some people say the store lost $200, others argue for $170 or $130. The real trick is that the brain can accidentally count the same $100 twice.

A man steals a $100 bill from a store register. Later, he returns and uses that same stolen $100 bill to buy $70 worth of products. The cashier gives him $30 in change. So, how much did the store actually lose?

The answer is **$100**.

The easiest way to understand it is to look at what the store has at the end. The thief takes $100 from the register, creating a $100 loss. But when he returns and spends that same bill, the $100 goes back into the register. The store then gives him $30 in change and hands over $70 worth of merchandise.

In other words, the stolen bill itself is no longer missing. What the store ultimately loses is **$70 in products plus $30 in cash**, which equals exactly $100. As the original explanation puts it, “The stolen $100 bill itself ended up back where it started: inside the register.”

That is why this simple riddle causes so many arguments. There are no complicated equations or difficult calculations involved. The challenge is simply following the money without counting the same $100 twice. “You simply need to carefully follow what is actually lost in the final outcome.” Once you see that, the answer becomes much easier to understand.