What is common among 11, 69, and 88?

What's the only room from which no one can enter or leave

Find the next number in the series.
1 10 24 43 67 ?

Move four matchsticks to the below square to form three squares?

A woman is sitting in her hotel room and hears a knock at the door. She opens the door to see a man whom she’s never met before. He says, “I’m sorry, I have made a mistake, I thought this was my room.” He then goes down the corridor and into the elevator. The woman goes back into her room and calls security. What made the woman so suspicious of the man?

Whats the next number in the below number sequence pattern.

P is the father of Q and S is the son of R. T is the brother of P and has a daughter U. If R is the sister of P, then what is the relation between U, Q and S?

Can you count the number of triangles in the picture below?

I have Rs.50 and I spend it in the way as below.

When it is alive we sing, when it is dead we clap our hands. What is it?