How can a man go eight days without sleep?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

A boy was locked in a room by some robbers. All that is in the room is a piano, a calendar, and a bed. The room is locked from the outside. What does he eat, drink, and how does he escape and get out?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

I am the largest in my family of fifty.
The youngest of our family lives separately from the rest of the family and so do I.
I am regarded as harsh and tough.
I am so large, you cut me in two equal halves,
each half would still be larger than the second largest member of the family.
Who am I?

Which flower has two lips?

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.

What does it mean?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

Look at the picture and find out which square is not linked with any of the other squares.