What do you call a fish without an eye?

What is next number in the pattern below:

131 517 192 123 ?

A man is found dead with a knife in his back When the investigation is done. A chair lays beside him and the forensic team finds moisture around the body.

If he committed suicide, how did he do it?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

If 1+9+8=1, what is 2+8+9?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

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.

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?