Brain Teasers!

Larry's father has five sons named ten, twenty, thirty and forty was is the fifth sons name

what goes up and down but remains in the same place?

Some months have 31 days, some have 30 days. how many months have 28 days?

What travels around the world but always stays in a corner?

There was an airplane crash, every single person died yet two survived. How is this possible?

What can you lead up the stairs but not down?