Why Aeroplane windows are round?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

The following "Brain Bat" means Slow Down.
S
L
O
W

Using the same logic, can you tell us what does the following Brain Bat means ?
E
V
I
G

Count the number of triangles in the below picture?

There are 3 apples in the basket and you take away 2. How many apples do you have now?

You have a square. What you have to do is cut and reassemble the square such that you create a Red Cross sign that has the same volume as that of the square.

There is something which is always coming but never arrives?

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?