Replace the question mark with the number below given a simple math problem.

If it took eight men ten hours to build a wall, how long would it take four men to build it?

A girl has as many brothers as sisters, but each brother has only half as many brothers as sisters. How many brothers and sisters are there in the family?

What number do you get when you multiply all of the numbers on a telephone's number pad?

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

Find The Missing Number In the Sequence.
6 25 64 ? 32 1

The captain of a ship is telling you an interesting story and then poses a question. He says, “I have travelled the oceans far and wide. One time, two of my sailors were standing on opposite sides of the ship. One was looking west and the other one east. And at the same time, they could see each other clearly. Can you tell me how that was possible?”

I am an eight letter word and I am a computer terminology.
The second, third and fourth letters make an animal.
The fourth, fifth, sixth, seventh and eighth letters make a weapon.
The first, second, third and fourth letters can be taken as an outcome of any exam.
The fifth, sixth, seventh and eighth letter combine to form a high end typing software.

Can you tell who am I ?

2, 3, 5, 9, 17, _ What is the next number in the sequence?

What number comes next in this sequence:
7 8 5 5 3 4 4 _