What goes up but never comes down?

Can you solve the below rebus?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

Today, I celebrated my 32nd birthday but I was born in 1972.
How is this possible?

If an electric train is travelling south, then which way is the smoke going?

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?

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

In a Society, there are over 100 flats.

Flat 1 is named the first flat.
Flat 2 is named the second flat.
Flat 3 is named the third flat. And So On.....

A visitor decides to walk through all the flats, and he finds all the flats except flat 62.
Anmol later founds that the locals of the town have given it another name.

What is the name of the Flat?

What is at the end of a rainbow?