Why Wine Glass Stem is so long?

Replace the question mark in the picture below.

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not rounded numerals equals 24.

I was born in a small house and I live in it all alone. No windows and no doors have been assigned to my house. The only way I can go out is by breaking through the walls of my house.

Who am I?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

What does an Island and the letter T have in common?

What begins with T, ends with T, and has T in it?

Find the next number in the sequence

5 12 24 36 ?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

How can you drop a raw egg from a height onto a concrete floor without cracking it?