Why Wine Glass Stem is so long?

Assume the given figure to be a delicious doughnut. Yes, now you can concentrate more on the puzzle. So you have this delicious doughnut in your refrigerator when your friends come knocking at the door. There are eight of them. Now you have to make three cuts in this doughnut so that each one of you nine people can enjoy a piece of it. Neither you nor your friends would mind the size of their piece as long as they are getting it. How will you do it?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Can you divide numbers from 1 to 9 (1 2 3 4 5 6 7 8 9) into two groups so that the sum of the numbers of each group is equal?

Note: 9 cannot be turned over to make it 6.

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

I am a five-letter word and comprises two different vowels and three same consonants. I am so strong that I can spoil your entire work.

Can you find out who am I?

How many triangles are there in the picture below?

There are forty elephants and they have forty-fore heads. How can this be possible?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

No matter how little or how much you use me, you change me every month. What am I?