Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

During which month do people sleep the least?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

What does a man do only once in his lifetime, but women do once a year after they are 29?

Arrange the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 above and below the division line in a manner that the thus formed fractions equal to 1/3.

(You can use one number only once)

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?