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

In the picture given below, can you find out which digit will take place of the question mark?

You are given 2 eggs.
You have access to a 100-storey building.
Eggs can be very hard or very fragile means it may break if dropped from the first floor or may not even break if dropped from 100th floor, Both eggs are identical.
You need to figure out the highest floor of a 100-storey building an egg can be dropped without breaking.
Now the question is how many drops you need to make. You are allowed to break 2 eggs in the process

What month of the year has 28 days?

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?

What brings you down but never up?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

If 24H in a D => 24 hours in a day.
What does "64S on CB" stand for?

An office is divided into 8 cubicles. How many of the cubicles are painted if only 1/8 of the cubicles are painted?