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

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

I am white when I am dirty, and black when I am clean. What am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

In an interview, a boy was asked an unusual question 'How two persons sitting with a table in between them can't see each other?' He was unable to reply. Can you?

How many letters are in the alphabet?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.