1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

What's the only room from which no one can enter or leave

You have two buckets - one holds exactly 5 gallons and the other 3 gallons. How can you measure 4 gallons of water into the 5 gallon bucket?

(Assume you have an unlimited supply of water and that there are no measurement markings of any kind on the buckets.)

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 goes up but never comes down?

What occurs twice in a week, once in a year but never in a day?

What does this simple rebus mean?

How is a fly different from a mosquito?

Our product and our sum always give the same answer. Who are we?

A network of 20 x 10 squares is given to you.

Can you calculate how many unique squares and rectangles can be formed combining two or more individual squares ?