If you say my name, I will no longer exist. What am I?

Given that

(78)^9 = 6
And (69)^4 = 11

Can you find out

(99)^2 =?

(Note: This is Logical, not Mathematical)

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

What do you see in the image below

P is the father of Q and S is the son of R. T is the brother of P and has a daughter U. If R is the sister of P, then what is the relation between U, Q and S?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

What has no start, end, or centre?

Can you place six X (crosses) in below board without making three in a row in any way ?

Why Aeroplane windows are round?