81 x 9 = 801. What must you do to make the this equation true?

What jumps when it walks and sits when it stands?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

The more of this there is, the less you see. What is it?

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.

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

It spends most of its day eating white, but when it’s quick enough, it gets to eat fruit and sometimes some blue things. It’s in a dark room, where the walls are blue, it runs from a ghost that roams the halls and haunts it all the time. What is it?

Why Wine Glass Stem is so long?