How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

Why do we preferably have round manhole covers and not square ones?

When it's bad luck to meet a black cat?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

What is the difference between a jeweller and a jailer?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

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

You need to remove two matchsticks to make the below equation true. Can you do it ?