What always comes into a house through the keyhole?

What is always in front of you but can’t be seen?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

What is the longest word in the dictionary?

What shoe company does this rebus represent?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

Two batsman each on 94 runs. Seven runs needed to win in last 3 balls. Both make 100*. How?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?