If eleven plus two equals one, what does nine plus five equal?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Which of the following words don't belong in the group and why?
CORSET, COSTER, SECTOR, ESCORT, COURTS

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.

How is the moon similar to a dollar?

John was visiting his friend Jacob. He found out that his friend's wife had just killed a burglar in self-defense.
John asks Jacob about what happened and he told that "His wife was watching television when suddenly the bell rang. She thought that it is her husband Jacob but she found the burglar who attacked her instantly and she got so frightened that she killed the burglar immediately with the knife.
John asked the police to arrest his friend's wife. Why?

You see me once in June, twice in November, and not at all in May. What am I?

The picture shows the dice results in each couple of throws. If they are actually following a pattern, can you find out the missing one?

What has hands, but can’t clap?

What jumps when it walks and sits when it stands?