What do you answer even though it never asks you questions?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

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?

Can you solve the rebus below?

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

81 x 9 = 801. What must you do to make the this equation true?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211