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

A man was gazing through the window of the 23rd floor of the building. He suddenly opened the window and jumped on the other side of the window. On landing on the floor, there was not a sheer mark of injury on him.

How can that be possible if he did not use any kind of parachute and did not land on a soft surface?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What does this mean?

CCCCCCC

What am I?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?