If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

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

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Can you solve this picture maths equation?

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

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.

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

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

You can see it everyday, But cannot touch it at will. What is it?

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?