You find yourself trapped in a mysterious room with two doors. One door leads to certain death, while the other leads to freedom—but you don’t know which is which.
Standing in front of the doors are two guards:
- One always tells the truth
- One always lies
You can only ask ONE question to one guard to figure out which door leads to freedom.
What do you ask?
Brain teaser solution
To solve this, you need to trick the liar into telling the truth! Here’s the magic question:
“If I were to ask the other guard which door leads to freedom, which door would they point to?”
Then, choose the opposite door!
Why Does This Work?
- If you ask the truthful guard, he knows the liar will point to the wrong door—so he tells you the wrong door.
- If you ask the lying guard, he knows the truthful guard will tell you the correct door—but since he always lies, he also points to the wrong door.
- No matter which guard you ask, they will always point to the wrong door!
So, all you have to do is take the opposite door, and you’re free!
Would you have figured it out?