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

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

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.

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Find The Odd One Out

1. FLOW
2. SNIP
3. TRAP
4. DRAW
5. BACK

There are a hundred statements.

First person says: At least one of the statements is false.

Second person says: At least two of the statements is false.

Third person says: At least three of the statements are false.

Fourth person says: At least four of the statements are false.

..

..

..

Hundredth person says: At least a hundred of the statements are false.

Analysing it, how many statements do you think are false and how many are true?

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?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?