How much has the shop owner lost altogether?
Take a moment to work it out before reading the explanation.
The Answer: $100
The shop owner’s total loss is $100, assuming the merchandise cost the shop $70 in value and the original bill was returned to the register during the purchase.
Here’s the breakdown:
- $70 in merchandise: The man leaves with goods worth $70.
- $30 in change: He also receives $30 in cash.
Adding these amounts gives:
$70 + $30 = $100
Although the shop owner gets the original $100 bill back, the transaction does not leave the owner with a net gain from the theft. The bill was taken from the register and then returned as payment for the merchandise.
Why the Puzzle Can Be Confusing
The trick is to avoid counting the same $100 bill twice.
At first, the shop loses $100 in cash. During the purchase, that same bill returns to the register, but the owner gives away $70 worth of merchandise and $30 in change.
The final loss is therefore the value of the goods and the cash handed over, totaling $100.
The original stolen bill is part of the sequence of events, not an additional loss to add on top of the merchandise and change.
A Simple Way to Solve Similar Puzzles
When working through a money riddle, focus on the final financial position rather than adding every amount mentioned in the story.
Ask yourself three questions:
- What money did the shop owner initially lose?
- What money or goods did the customer receive?
- Which amounts were returned or exchanged during the transaction?
Following the movement of the money helps prevent double-counting and makes the answer easier to understand.
Final Thoughts
This classic shop riddle is a useful exercise in logical thinking. Its solution becomes clearer when you separate the initial theft from the later purchase and consider the shop owner’s overall loss.
The key lesson is simple: track what changes hands, account for what comes back, and avoid counting the same money more than once.