What is the number written at the end of some names?

As far as I can tell there is [Title/Suffix] [First Name] [Last Name/Surname] [Number].

I am confused on two things really:

  • What do you call the last part of someone's name like "III" for 'the third'?
  • Why do they call Mr./Mrs./etc the suffix of a name when it is actually the first part of the name?

Solution 1:

You have it backwards. II/JR.... are the suffix. Mr, Mrs. are the Title or prefix

Solution 2:

The answer is in Wikipedia. They are called suffixes, and more specifically generational suffixes. These are Sr., Jr., II, III, IV, etc.