How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

John is found dead in a bare field. Nobody killed John,
John did not commit suicide.

Inspector Jacob found a bag just a few meters away from John which could save his life. What was in the bag?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

Before Balboa discovered the Pacific Ocean, which was the largest ocean before that?

I have teeth but i don't bite. Who Am I ?

A man is lying dead in a field where no one is around. His head is split open and his legs are disfigured. Near to him, there is an unopened package. No living organism can be found anywhere at the crime scene.

How did he die?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?

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