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

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

I have an eye but still cannot see.

Who am I?

Lifeless eyes on my smiling face and watch your child's sleeping place. In their dreams they hold me tight. What am I?

A blonde put eyeliner on her head. Why?

Can you spot the man between the coffee bean in the picture below ?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

The more you take me, the more you leave me behind.
Who Am I?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?