Can you replace the question mark with the correct number in the below table sequence?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

How do you go from 98 to 720 using just one letter?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

If two fifty-foot ropes are suspended from a forty-foot ceiling that is twenty feet apart, how much rope will you be able to steal if you have a knife?

Which is the rope you never skip with?

A man is trapped in a room. The room has only two possible exits doors. Through the first door there is a room constructed from magnifying glass. The blazing hot sun instantly fries anything or anyone that enters. Through the second door there is a fire-breathing dragon. How does the man escape?

How can you take 2 from 5 and leave 4?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?