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

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

A mother bought three dress for her triplets daughters(one for each) and put the dresses in the dark. One by one the girls come and pick a dress.
What is the probability that no girl will choose her own dress?

A beggar on the street can make one cigarette out of every 6 cigarette butts he finds. After one whole day of searching and checking public ashtrays the beggar finds a total of 72 cigarette butts. How many cigarettes can he make and smoke from the butts he found?

Andrew sees a very rare bird named "Ruppell's vulture". Soon Andrew was dead. Can you explain the mystery, Mr. Sherlock?

What number when divided in half becomes zero?

I can be cracked, made, told, and played. What am I?

Spot 5 differences in two Christmas tree below:

What has many teeth, but cannot bite?

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E