Firstly

Convert between the twelve forms of numeric, written and ordinal numbers:

From   To     Use
--------------------------------
1      one    NumToNumber()
1      1st    NumToOrd()
1      first  NumToOrdinal()
one    1      NumberToNum()
one    1st    NumberToOrd()
one    first  NumberToOrdinal()
1st    1      OrdToNum()
1st    one    OrdToNumber()
1st    first  OrdToOrdinal()
first  1      OrdinalToNum()
first  one    OrdinalToNumber()
first  1st    OrdinalToOrd()

Each function accepts an optional second parameter to control the
capitalisation of the return value (where appropriate):

Value  Means
-----------------------------
0      all lower case
1      Leading capital letter
2      Title Case
3      ALL CAPS

Requires Salman Halim's NumberToEnglish plugin:
http://www.vim.org/scripts/script.php?script_id=2561

NOTE: The NumberToEnglish plugin (at least version 1.4 does) might have CRLF
      line terminators which cause an error message on unix systems. Use
      dos2unix to fix this problem.