why number 8549176320 is one of a kind?
I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?
If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?
There are 2 sand hourglasses. The small one can measure 5 hours and the large one can measure 7 hours. How can we measure 16 hours with 2 sand hourglasses running together ?
You can hear me, but you can't touch or see me. What am I?
I throw two dice simultaneously. What is the probability of getting a sum as 9 of the two numbers shown?
If eleven plus two equals one, what does nine plus five equal?
The more of this there is, the less you see. What is it?
All of Jacob's shoes are red except two. All of Jacob's shoes are green except two. All of Jacob's shoes are yellow except two. How many shoes does Jacob have?
How is the moon similar to a dollar?
As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.
There is a cryptic organization called Cicada 3301 that posts challenging puzzles online, possibly to recruit codebreakers and linguists.