What is both possible and impossible at the same time?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

On a magical land of Mexico , all the animal in the land are rational.

There are 10 tigers and one goat.
Tiger can eat goat but since it's a magical land , the tiger who eats the goat , turns into goat and then can be eaten by the remaining tiger(s).

If we leave them for some time then how many goat and tiger will be there , when we come back ?

There were five men at church, and it started raining while they were outside. The four that ran still got wet, but the one that was still stayed completely dry. Why did he stay dry?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

A non-stop marathon is the shared favourite sport of three brothers.

*The oldest one is fat and short and trudges slowly on.
*The middle brother's tall and slim and keeps a steady pace.
*The youngest runs just like the wind, speeding through the race.

"He is young in years, we let him run!" the other two brothers explained, "'because though he is surely number one, he is second, in a way." Why is it?

What is the riddle which can be asked all day with a different correct answer each time.

2, 3, 5, 9, 17, _ What is the next number in the sequence?

Can you solve below mathematical equation?

2^1234 - 2^1233