Here’s a simple-looking riddle that has caused plenty of arguments online.

Read it carefully before checking the answer:

A man walks into a shop and steals a $100 bill from the register.

A little later, he returns to the same shop.

This time, he uses that same $100 bill to buy $70 worth of merchandise.

The shop owner accepts the $100 bill and gives the man:

• $70 worth of goods
• $30 in change

The man leaves.

How much money did the shop owner lose?

Was it:

A) $30

B) $70

C) $100

D) $170

Take a moment before answering.

The wording makes the problem seem more complicated than it actually is.

The Answer Is $100

The shop owner’s total loss is:

$100

Here’s why.

Step 1: The Man Steals $100

Initially, the thief takes a $100 bill from the cash register.

At this moment, the shop is down:

$100

Simple enough.

But the story isn’t over.

Step 2: He Brings the Same $100 Back

The thief later returns to the store and purchases $70 worth of merchandise using the same $100 bill he stole.

This detail is crucial.

When he hands that $100 bill back to the shop owner, the stolen $100 physically returns to the register.

So you can’t count that original $100 as permanently missing and then add everything from the purchase on top of it.

Doing that would count part of the loss twice.

Step 3: The Owner Gives Him $30 in Change

The merchandise costs $70.

The thief pays with the stolen $100 bill.

So the shop owner gives him:

$30 in change.

Now the thief leaves with $30 of the shop’s cash.

That’s a real loss.

Step 4: He Also Leaves With $70 Worth of Merchandise

The thief also takes the goods he supposedly purchased.

Those goods are valued at:

$70

So the business has lost:

$30 in cash + $70 in merchandise

Do the math:

$30 + $70 = $100

That’s the total loss.

Why Isn’t the Answer $200?

This is where many people get caught.

They reason:

The man stole $100.

Then he got $70 in merchandise.

Then he received another $30.

So:

$100 + $70 + $30 = $200

But that’s incorrect.

Why?

Because the original $100 wasn’t still missing when the man left the second time.

He returned it when he used it to make the purchase.

You’re counting the same $100 twice.

Why Isn’t It $170?

Another common answer is:

$100 stolen + $70 merchandise = $170

That has the same problem.

The stolen $100 came back to the register.

It wasn’t an additional final loss.

The Easiest Way to Solve It

Forget about all the transactions for a moment.

Instead, ask one simple question:

What did the thief ultimately leave the store with?

He left with:

$70 worth of merchandise

plus

$30 in cash

Therefore:

$70 + $30 = $100

That’s everything he gained from the shop.

And it’s everything the shop ultimately lost.

Another Way to Look at It

Imagine the shop initially has:

$1,000 in cash + its merchandise

The thief steals $100.

Cash becomes:

$900

Then he returns and hands that same $100 to the owner.

Cash returns to:

$1,000

The owner then gives him $30 change.

Cash becomes:

$970

So the store has lost:

$30 cash

But the thief also leaves with:

$70 merchandise

Therefore:

$30 cash loss + $70 inventory loss = $100 total loss.

The Trick Is in the Story, Not the Math

The arithmetic is extremely simple.

What makes the riddle difficult is the sequence of events.

The $100 disappears.

Then it comes back.

Then $30 leaves.

Then $70 worth of merchandise leaves.

If you treat every movement as a separate loss, you’ll end up with the wrong answer.

Instead, look at the final position of the business.

The shop owner is missing:

$30 in cash

and

$70 worth of goods.

Final Answer: $100

The thief walks away with exactly $100 of value belonging to the business.

$70 in merchandise + $30 cash = $100 total loss.

Now here’s the real question:

Did you get $100 on your first try, or did the riddle trick you into choosing $170 or $200?