What does this rebus riddle means ?

Complete the series by replacing "?" with the correct number.

ST ND RD TH '?'

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

What breaks yet never falls, and what falls yet never breaks?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

I am Huge on Sunday and Saturday.
I am small from Tuesday to Thursday.
I do not exist on Monday and Friday.
Who am I?

What Time Should the last watch show in the below figure?