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

which number am I?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

All of the flowers I have are orchids except two. All of the flowers I have are hibiscuses except two. All of the flowers I have are roses except two.

Can you tell me how many flowers I have?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

Imagine you are in a room with no windows or doors. How will you get out?

Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

How many times in a given day, minutes and hour clock comes in a straight line ?

There are six people in a family namely M, N, O, P, Q and R.

R and O are brother and sister.

N is the brother of Q's husband.
P is the father of M and grandfather of R.

How many male members are in the family?