How can you make number one disappear by adding something to 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 ?

Can you replace the question mark with the correct number?

John has eleven friends. He has a bowl containing eleven apples. Now He wants to divide the eleven apples among his friends, in such a way that an apple should remain in his bowl.
How can He do it?

Solve the mathematical equation in the picture below.

Count the number of squares in the picture below.

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

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

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

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?