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

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

One evening there was a murder in the home of a married couple, their son and daughter. One of these four people murdered one of the others. One of the members of the family witnessed the crime.

The other one helped the murderer.

These are the things we know for sure:

1. The witness and the one who helped the murderer were not of the same sex.

2. The oldest person and the witness were not of the same sex.

3. The youngest person and the victim were not of the same sex.

4. The one who helped the murderer was older than the victim.

5. The father was the oldest member of the family.

6. The murderer was not the youngest member of the family.

Who was the murderer?

Prove that the below maths equation is true.

8 + 8 = 91

What number do you get when you multiply all of the numbers on a telephone's number pad?

A Shopkeeper collects 71 rupees in the form of 20 paisa and 25 paisa.
He collects a total of 324 coins.

Can you tell me how many number of 20-paisa and 25-paisa he got?

If 21x = 79x, what is the value of x?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?