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.

Prove that the below maths equation is true.

8 + 8 = 91

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

John is the son of Jacob.
So,
Jacob is the_____of John's father?

Replace the question mark with the number below given a simple math problem.

What does this rebus puzzle means ?

A pack of cards has 40 cards. You are blindfolded. Out of 40, 25 cards are facing down while 15 are facing up. You have been asked to divide this pack of cards into two decks - so that each deck contains an equal number of face-up cards. Remember, you are blindfolded.

How will you do it?

A sundial has the fewest moving parts of any timepiece. Which has the most?

Can you name some countries which do not have the alphabet 'A' in them?