What is the next number in this matchsticks series riddle?

There is a place where if I stand up straight, I will still be considered sideways.

When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?

People make me, save me, change me, raise me. What am I?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

Find the next number in the series below

21 32 54 87 131 ?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

The Little ant seems to be always confused. Do you know why?

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?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.