Why Aeroplane windows are round?

What does this rebus riddle means ?

You can win me and lose me but never buy me
You can not eat me and never want to part with me
I can make you cry or bring you joy
I am not a machine and definitely not a toy
You keep me but i am not forever just yours
You might find me in a case or on a shelf next to a vase
I am hard and i am tall if you bump me i am sure to fall
I am made of different materials and am at many events
If your lucky and fight hard I might be yours
What am I ?

Out of three Friends John, Jacob and Jonny one of them is a king, one is a bureaucrat, and one is a Spy.

The king always tells the truth, the bureaucrat always lies, and the Spy can either lie or tell the truth.

John says: Jonny is a bureaucrat
Jacob says: John is a king
Jonny says: I am a Spy

Tell me, Who is the king, who is the bureaucrat, and who is the Spy?

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

What demands an answer, but asks no questions

What is the next number in the series?

15 29 56 108 208 ?

It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
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* * *