SOLUTION: The following letters represent a series. What letter do you think comes next? I, O, V, F, X, T, L, F, M, _

   The Roman numeral for 1 is I. 
     and "one" starts with an O.
   The Roman numeral for 5 is V. 
    and "five" starts with an F.
  The Roman numeral for 10 is X. 
      and "ten" starts with a T.
  The Roman numeral for 50 is L. 
   and "fifty" starts with an F.
_______________________________.
_______________________________.
The Roman numeral for 1000 is M. 
 and "thousand" starts with a T.

But I can't help but wonder why they skipped C for 100,
and went from L for 50 all the way to M for 1000.
They were in order of the letters used I,V,X,L, but next
should have been C followed by H.  But they skipped those.
That's why I left those two rows blank.  They should be

 The Roman numeral for 100 is C. 
 and "hundred" starts with an H.

Oh well!

Edwin