A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

In a stable, there are men and horses. In all, there are 22 heads and 72 feet. How many men and how many horses are in the stable

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

What is the centre of gravity?

Replace the 'X' with any mathematical symbol to make the expression equal to 111.

18 X 12 X 2 X 3 = 111

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Move four matchsticks to the below square to form three squares?

What you cannot hold but it is yours?

What goes through cities and fields, but never moves?