What has to be broken before you can use it?

Can you solve this picture maths equation?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

What breaks yet never falls, and what falls yet never breaks?

How many times can you subtract the number two from the number fifty?

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?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?