Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

Can you count the number of matches in the picture below ?

I’m tall when I’m young, and I’m short when I’m old. What am I?

I don't get anymore wetter, no matter how much rain falls on me.

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

A generous owner of a company decided to give a bonus of $45 to every man and $60 to every woman on his birthday. But only one-ninth of the men and one-twelfth of the women were present to take the bonus.

Can you calculate the amount of money the owner spent if there were 3552 employees?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

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?