HardMath Riddle
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?
Riddle
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?
Choose an answer
A.500
B.250
C.1
D.22
Hint: It's a word with 0 letters, starting with "2".
Answer
22
Why this is the answer
Only coffins with an odd number of divisors stay open in the end - the perfect squares - and there are exactly 22 perfect squares (1 squared through 22 squared) at or below 500.
This riddle is filed under Math Riddles and rated Hard.