A seemingly simple math puzzle has left thousands of people scratching their heads. The question begins with a man entering a small neighborhood shop and secretly stealing a $100 bill from the cash register. Instead of leaving for good, the man returns a short time later and uses that exact same $100 bill to purchase $70 worth of merchandise. The unsuspecting shop owner accepts the money and gives him $30 in change. The question is simple: how much did the shop owner actually lose?

At first glance, many people immediately answer $200. Their reasoning is that the thief originally stole $100 and then returned to take another $70 in merchandise along with $30 in change. When all those amounts are added together, the total appears to be $200. However, this calculation overlooks one important detail that completely changes the answer.

Imagine the shop owner counting his cash before the incident. The thief removes $100 from the register, leaving the business $100 short. But when the thief returns to make his purchase, he hands that same $100 bill back to the shop owner. The stolen money has now returned to the register, meaning the original cash shortage has been canceled out. This is the crucial part of the puzzle that many people miss.

The real loss happens during the second transaction. The thief walks away with $70 worth of goods and receives $30 in change. Because the $100 bill used for the purchase originally belonged to the shop, the thief has effectively obtained both the merchandise and the change without paying anything of his own. Adding the $70 in goods to the $30 in cash gives a total loss of exactly $100. The original stolen bill cannot be counted twice because it was returned during the purchase.

The correct answer is $100. The shop owner lost $70 worth of merchandise and $30 in cash, for a combined loss of $100. This clever little puzzle demonstrates how easily people can become confused when the same money moves through several transactions. The secret is to follow what the shop owner ultimately has left rather than adding every movement of cash together. Once that distinction becomes clear, the answer is surprisingly straightforward.