How can you take 2 from 5 and leave 4?

Can you find the missing piece of the Porsche?

When can we add 2 to 11 and get 1 as the correct answer?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

What is next number in the pattern below:

131 517 192 123 ?

What time is it when an elephant sits on a fence?

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?

If a boy blows 18 bubbles,
Then pops 6 eats 7 and then
He pops 5 and blows 1.
How many are left?

I know a nine-letter word having only one vowel.
Do you ?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?