What does this rebus mean?

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Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

Can anyone tell me a word in the English dictionary which has a silent 'z'?

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?

If EELS + MARK + BEST + WARY = EASY

What does HELP + BARK + WARD + LEAD equal?

Who is that with a neck and no head, two arms and no hands? What is it?

How is a fly different from a mosquito?

We are a group of eight brothers. We consider the weak, yet we protect the king in every battle. If we move ahead, we never turn back. Who are we?