The $100 Riddle That Fools Almost Everyone

 

Some brain teasers look incredibly easy until you actually try to solve them. They present a familiar situation, give you a few simple numbers, and somehow make you question even the most basic arithmetic.

This $100 riddle is a perfect example.

Imagine you're running a small shop when a man walks in, takes a $100 bill from your cash register, and disappears. You might think the story ends there, but a little later, the same man returns.

This time, he picks up $70 worth of merchandise and hands you a $100 bill to pay for it. You accept the money, put it in the register, and give him $30 in change.

The man leaves with the merchandise and the $30.

Now comes the interesting question:

How much has the shopkeeper actually lost?

Is it $100, $130, $170, or even $200?

Take a moment to think about it before reading further. The answer may be simpler than you expect, but the way the transactions fit together is what makes this puzzle so confusing.

The $100 Riddle: What Happened?

Let's go through the situation carefully.

A man steals $100 from a shopkeeper's cash register. Later, he returns and uses that same $100 bill to purchase $70 worth of goods.

The shopkeeper accepts the bill and gives him $30 in change.

The thief then walks away with $70 worth of merchandise and $30 in cash.

At first, it might seem as though the shopkeeper has lost the original $100, another $70 in merchandise, and $30 in change.

But there's an important detail: the $100 bill used for the purchase is the same bill that was stolen earlier.

That changes the calculation completely.