Which number should replace the question mark?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

Look at me. I can bring a smile to your face, A tear to your eye, Or even a thought to your mind. But, I can't be seen. What am I?

Solve this tricky question. You are trapped in a forest. With you, you have a gun preloaded with two bullets in it. In front of you, there is a tiger, a leopard and a jaguar.

How do you survive?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

I don't get anymore wetter, no matter how much rain falls on me.

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.