What has no start, end, or centre?

What always comes into a house through the keyhole?

If a wheel has 54 spokes, how many spaces are there between the spokes?

Why do you find that most of the buildings are deprived of the 13th floor?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

An equation has been laid down using a few matchsticks. However, as you can see, the equation is not correct. Can you correct the equation if you are allowed to add or remove 5 matchsticks?

You have a roll of cloth 1km long. You have a machine which cuts this roll into pieces of 10-meter-long cloth.

How long would it take for the machine to cut the roll if each cut took 4 secs?

You need to move three matchsticks to form three squares. Can you do it?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?