What work can one never finish?
Why Aeroplane windows are round?
There are forty elephants and they have forty-fore heads. How can this be possible?
Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator. Do you ?
What 5-letter word typed in all capital letters can be read the same upside down?
Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.
Identify the hidden meaning behind this picture?
If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten. How is this possible?
What breaks yet never falls, and what falls yet never breaks?
Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?
Nine marbles are arranged in the image below. Can you slide two marbles to form a square?
There is a cryptic organization called Cicada 3301 that posts challenging puzzles online, possibly to recruit codebreakers and linguists.