How can a man go eight days without sleep?

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

which number am I?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

In a school, 280 students studied chemistry, 254 students studied physics and 280 students studied biology.

97 students studied chemistry as well as physics, 138 students studied physics as well as biology and 152 students studied chemistry as well as biology.

73 students studied all the three branches.

Can you find out the total number of students?

What happened when the wheel was invented?

Solve The below Equation:

ALFA + BETA + GAMA = DELTA

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

Can you solve this picture maths equation?

In the four images below, can you find the odd one out?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?