How many coffins are open - Math Riddle

Riddles often carry a mysterious charm, inviting us to unravel enigmatic scenarios. Today, we have a perplexing situation involving 500 coffins and 500 men. The challenge is to determine how many coffins remain open after a series of actions. Join us as we delve into this intriguing puzzle.


There are 500 coffins and 500 men who need them. The undertaker asks the first man to go to every coffin and open them. Then he tells the second man to go to every one and close it. The third one goes to every third coffin and so on.

How many are open?


Answer: 22

Explanation :  

Certainly, let's provide a mathematical explanation for the answer:

Initially, we have 500 coffins, and each of them is open.

The process involves 500 men who will perform actions on the coffins. We need to determine which coffins remain open.

To find the coffins that stay open, we consider the square root of the total number of coffins, which is √500.

Calculate the square root of 500:

√500 ≈ 22.36

The square root gives us a decimal value, but for this puzzle, we are interested in the whole number part, which is 22.

So, 22 coffins will remain open because they are the ones that have an odd number of actions performed on them.


√500 ≈ 22.36

Therefore, the answer is indeed 22 coffins that stay open.




Solving this coffin conundrum was a journey of logic and pattern recognition. It serves as a reminder that riddles and puzzles can be excellent exercises for our minds, encouraging us to think critically and uncover hidden solutions. The next time you encounter a brain teaser, remember to break it down step by step, and you might just unveil its secrets. Happy puzzling!