In which direction should the missing arrow point?

Name a key which is hardest to turn.

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

Complete the table series riddle by finding the number that can replace "??".

You bought me for dinner but never eat me. What am I?

What occurs twice in a week, once in a year but never in a day?

A woman lives in a Tall building thirty-six floors high and served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?