This seemingly simple math puzzle has become a favorite online because it looks easy at first, yet often leads to surprisingly heated disagreement. The setup involves a thief, a stolen $100 bill, a later purchase, and change handed back during the transaction. While the story appears straightforward, the challenge comes from tracking what the store actually loses by the end.

The scenario begins when a thief takes $100 directly from a store’s cash register. At that moment, the business is short $100 in cash. Later, the same person returns and uses that stolen bill to buy $70 worth of merchandise. Since the cashier does not know the money was stolen, the transaction is treated like a normal sale.

The confusing part comes when the cashier accepts the $100 bill and gives the thief $30 in change. Many people start adding every part of the story separately—the stolen bill, the merchandise, and the change—without accounting for the fact that the same $100 bill returns to the register. This is why different answers often appear in comment sections.

The store’s final loss is $100: $70 worth of goods plus $30 in change. The stolen bill came back, so it cancels out as cash inside the register. What the thief ultimately walks away with is merchandise valued at $70 and $30 cash, making the total loss to the store $100.