A man walks into a shop and steals a $100 bill from the cash register. He then uses the same bill to buy $70 worth of merchandise. The shop owner accepts the money without realizing it was stolen and gives the man $30 in change. The question is simple: how much money does the shop owner lose in total?

At first, the puzzle may seem confusing because the same $100 bill is involved in both the theft and the purchase. Some people add the stolen money, the merchandise, and the change together, arriving at a higher amount. However, the trick is to follow what the thief actually takes from the shop without counting the same money twice.

The correct answer is $100. The thief walks away with $70 worth of merchandise and $30 in cash. Together, these add up to $100, representing the shop owner’s total loss. Although the owner receives the stolen bill back during the purchase, it does not create a genuine financial gain because that money originally belonged to the shop.

The easiest way to solve the riddle is to focus on the final result rather than every step of the transaction. The thief keeps the goods and the change, while the shop owner loses both. Adding the original stolen bill again would count the same money twice and lead to an incorrect answer.

This brain teaser is a useful reminder that simple money puzzles can be surprisingly tricky. Instead of rushing to calculate, ask yourself one question: what does the thief leave with that belongs to the shop? Once you identify the merchandise and the change, the answer becomes clear. The shop owner loses $100 in total, not $170 or $200.