Imagine running a small neighborhood store on an ordinary afternoon. Customers are coming and going, and everything seems perfectly normal. Suddenly, someone quietly takes a $100 bill from your cash register without you noticing. You continue working, completely unaware that anything has happened. But what this person does next creates a surprisingly tricky math puzzle!

A short time later, the same person returns to your store and begins shopping. They select several items with a total price of $70. When they reach the checkout counter, they hand you a $100 bill. You accept the money, place it in your register, and give them $30 in change. The customer then walks away with the merchandise and the cash.

Only afterward do you discover that the $100 bill used to pay for those items was actually the same bill stolen from your register earlier! Now you’re left wondering how much money your business has lost. Some people immediately answer $200, while others believe the loss is $170 or $130.

The secret to solving this puzzle is understanding what happened to the original $100 bill and what the customer ultimately took away. It sounds simple, but this classic brain teaser continues to confuse people because the same money appears in two different transactions.

BRAIN CHALLENGE: How much did the shopkeeper actually lose?

A) $100 | B) $130 | C) $170 | D) $200

Write your answer in the comments before checking what everyone else thinks