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

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

Which Burger Is Different in below image?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

The more of this there is, the less you see. What is it?

I have no life, but I can die. What am I?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?