The switches do have limitations.

For the currency, the following macro will handle up to
$999,999,999,999,999.99

Function ConvertCurrencyToEnglish(ByVal MyNumber)
Dim Temp
Dim Dollars, Cents
Dim DecimalPlace, Count

ReDim Place(9) As String
Place(2) = " Thousand "
Place(3) = " Million "
Place(4) = " Billion "
Place(5) = " Trillion "

MyNumber = Trim(Str(MyNumber))

DecimalPlace = InStr(MyNumber, ".")
If DecimalPlace > 0 Then
   Temp = Left(Mid(MyNumber, DecimalPlace + 1) & "00", 2)
   Cents = ConvertTens(Temp)
   MyNumber = Trim(Left(MyNumber, DecimalPlace - 1))
End If
Count = 1
Do While MyNumber <> ""
   'convert last 3 digits to English Dollars
   Temp = ConvertHundreds(Right(MyNumber, 3))
   If Temp <> "" Then Dollars = Temp & Place(Count) & Dollars
   If Len(MyNumber) > 3 Then
       'remove last 3 comverted digits
       MyNumber = Left(MyNumber, Len(MyNumber) - 3)
   Else
       MyNumber = ""
   End If
   Count = Count + 1
Loop

'clean up dollars
Select Case Dollars
   Case ""
       Dollars = "NoDollars"
   Case "One"
       Dollars = "One Dollar"
   Case Else
       Dollars = Dollars & " Dollars"
End Select

'clean up cents
Select Case Cents
   Case ""
       Cents = " And No Cents"
   Case "One"
       Cents = " And One Cent"
   Case Else
       Cents = " And " & Cents & " Cents"
End Select
ConvertCurrencyToEnglish = Dollars & Cents
End Function
=================================================
Private Function ConvertHundreds(ByVal MyNumber)
Dim Result As String
If Val(MyNumber) = 0 Then Exit Function

'append leading zeros to number
MyNumber = Right("000" & MyNumber, 3)

'do we have hundreds place digit to convert?
If Left(MyNumber, 1) <> "0" Then
   Result = ConvertDigit(Left(MyNumber, 1)) & " Hundred "
End If

'do we have tens place digit to convert?
If Mid(MyNumber, 2, 1) <> "0" Then
   Result = Result & ConvertTens(Mid(MyNumber, 2))
Else
   'if not, then convert the ones place digit
   Result = Result & ConvertDigit(Mid(MyNumber, 3))
End If
ConvertHundreds = Trim(Result)
End Function
======================================================
Private Function ConvertTens(ByVal MyTens)
Dim Result As String
'is value between 10 and 19?
If Val(Left(MyTens, 1)) = 1 Then
   Select Case Val(MyTens)
       Case 10: Result = "Ten"
       Case 11: Result = "Eleven"
       Case 12: Result = "Twelve"
       Case 13: Result = "Thirteen"
       Case 14: Result = "Fourteen"
       Case 15: Result = "Fifteen"
       Case 16: Result = "Sixteen"
       Case 17: Result = "Seventeen"
       Case 18: Result = "Eighteen"
       Case 19: Result = "Nineteen"
       Case Else
   End Select
Else
   Select Case Val(Left(MyTens, 1))
       Case 2: Result = "Twenty "
       Case 3: Result = "Thirty "
       Case 4: Result = "Forty "
       Case 5: Result = "Fifty "
       Case 6: Result = "Sixty "
       Case 7: Result = "Seventy "
       Case 8: Result = "Eighty "
       Case 9: Result = "Ninety "
       Case Else
   End Select

   'convert ones place digit
   Result = Result & ConvertDigit(Right(MyTens, 1))
End If
ConvertTens = Result
End Function
======================================================
Private Function ConvertDigit(ByVal MyDigit)
Select Case Val(MyDigit)
   Case 1: ConvertDigit = "One"
   Case 2: ConvertDigit = "Two"
   Case 3: ConvertDigit = "Three"
   Case 4: ConvertDigit = "Four"
   Case 5: ConvertDigit = "Five"
   Case 6: ConvertDigit = "Six"
   Case 7: ConvertDigit = "Seven"
   Case 8: ConvertDigit = "Eight"
   Case 9: ConvertDigit = "Nine"
   Case Else: ConvertDigit = ""
End Select
End Function
===========================================================
Sub TestAboveFunction()
Dim MyNumber
MyNumber = 551521896.32
MsgBox ConvertCurrencyToEnglish(ByVal MyNumber)
End Sub
===========================================================

Yes, unfortunately \*Cardtext only deals with whole numbers as you noticed.

To do better you would probably either need to split the number up into the
whole number and the fractional parts, and generate the exact wording you
need using more than one field. Alternatively, if the number of different
possible percentages is finite, and preferably small (e.g. because they can
only be 0.5, 1, 1.5, 2, up to a known maximum) then you might be better off
simply creating a sequence of IF fields, along the lines of

{ IF { MERGEFIELD myfield } = 5 "five percent (5%)" ""
}{ IF { MERGEFIELD myfield } = 5.5 "five and one half percent (5.5%)" ""
}

etc. Don't try to nest the fields as there is a limit of around 20 levels of
nesting.

As long as the pattern of words is the same for numbers above a million
(e.g. 999,000,000 should be written Nine hundred ninety nine million" - in
the UK we have an "and" which doesn't appear when you use
Cardtext/Dollartext) then you can try something like the following, which
should take you up to 999999999999

{ SET x { MERGEFIELD mylargenumber }
}{ SET r { =MOD(x,1000000) }
}{ SET m { =INT(x-r)/1000000)) }
}{ IF { m } = 0 "" "{ m \*Cardtext } million }" }{ r \Cardtext }

I think you can probably modify that if you need to use the word "billion"

Peter Jamieson