Which number should replace the question mark?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.

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

I am a ten letters word
The first four letters have the power to rule,
Next, four-letter can be eaten.
The next three-letter represents a lady.
I can fly as well

what am I looking for?

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

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

What has lots of eyes, but can’t see?

How many triangles are there on the puzzle below?

As we know that white starts the game of chess. Can you find the scenario shown in the picture below is possible when all the white pieces are at the original place while the black pawn is not as in the below picture?