Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

A kind heart person buy packed food at 3$/packet from United states and sells them at 1$/packet at Africa. After some time he becomes a millionaire.

How come the guy become millionaire ?

You are an expert on paranormal activity and have been hired to locate a spirit haunting an old resort hotel. Strong signs indicate that the spirit lies behind one of four doors. The inscriptions on each door read as follows:

Door A: It's behind B or C
Door B: Its behind A or D
Door C: It's in here
Door D: It's not in here

Your psychic powers have told you three of the inscriptions are false, and one is true. Behind which door will you find the spirit?

What is the longest word in the dictionary?

How is the moon similar to a dollar?

A man dies of old age on his 25 birthday. How is this possible?