What number when divided in half becomes zero?

Our product and our sum always give the same answer. Who are we?

How many words can a quill made with the feather of a pigeon write with a 100ml bottle of black ink?

It belongs to you, but other people use it more than you do. What is it?

Why blonde cannot dial 911?

Find out the missing number in the picture attached:

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Can you move from MANILA to UGANDA in the shortest time? You need to follow the below rules:
Rule 1: You can change up to 3 alphabets at a time.
Rule 2: New words must be of 6 alphabets.
Rule 3: The new word formed must be a country or capital.

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

Three people check into a hotel. They pay $60 for the rent of the room. After they check-in, the manager realize that the rent for the room is $55. So, he gives $5 to the bellboy and asks him to give it to them. The bellboy thinks that it will be difficult for the three people to share $5 among them and seeking the personal benefit, he pockets $2 and gives the remaining $3 to them.

Now, each person paid $20 and got back $1. In this manner, each of them paid just $19 which totals to the amount of $57. The bellboy has $2 with him and adding them, we get $59. So where is the remaining $1?