Can you find the missing piece of the Porsche?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

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?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

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

If eleven plus two equals one, what does nine plus five equal?

How can you take 2 from 5 and leave 4?

What has many keys but can’t open a single lock?