Convert currency into words

Function English(ByVal N As Currency) As String

    Const Thousand = 1000@
    Const Million = Thousand * Thousand
    Const Billion = Thousand * Million
    Const Trillion = Thousand * Billion

    If (N = 0@) Then English = "zero": Exit Function

    Dim Buf As String: If (N < 0@) Then Buf = "negative " Else Buf = ""
    Dim Frac As Currency: Frac = Abs(N - Fix(N))
    If (N < 0@ Or Frac <> 0@) Then N = Abs(Fix(N))
    Dim AtLeastOne As Integer: AtLeastOne = N >= 1

    If (N >= Trillion) Then
        Debug.Print N
        Buf = Buf & EnglishDigitGroup(Int(N / Trillion)) & " trillion"
        N = N - Int(N / Trillion) * Trillion
        If (N >= 1@) Then Buf = Buf & " "
    End If

    If (N >= Billion) Then
        Debug.Print N
        Buf = Buf & EnglishDigitGroup(Int(N / Billion)) & " billion"
        N = N - Int(N / Billion) * Billion
        If (N >= 1@) Then Buf = Buf & " "
    End If

    If (N >= Million) Then
        Debug.Print N
        Buf = Buf & EnglishDigitGroup(N \ Million) & " million"
        N = N Mod Million
        If (N >= 1@) Then Buf = Buf & " "
    End If

    If (N >= Thousand) Then
        Debug.Print N
        Buf = Buf & EnglishDigitGroup(N \ Thousand) & " thousand"
        N = N Mod Thousand
        If (N >= 1@) Then Buf = Buf & " "
    End If

    If (N >= 1@) Then
        Debug.Print N
        Buf = Buf & EnglishDigitGroup(N)
    End If

    If (Frac = 0@) Then
        Buf = Buf & " exactly"
    ElseIf (Int(Frac * 100@) = Frac * 100@) Then
        If AtLeastOne Then Buf = Buf & " and "
        Buf = Buf & Format$(Frac * 100@, "00") & "/100"
    Else
        If AtLeastOne Then Buf = Buf & " and "
        Buf = Buf & Format$(Frac * 10000@, "0000") & "/10000"
    End If

    English = Buf
End Function

Private Function EnglishDigitGroup(ByVal N As Integer) As String

    Const Hundred = " hundred"
    Const One = "one"
    Const Two = "two"
    Const Three = "three"
    Const Four = "four"
    Const Five = "five"
    Const Six = "six"
    Const Seven = "seven"
    Const Eight = "eight"
    Const Nine = "nine"
    Dim Buf As String: Buf = ""
    Dim Flag As Integer: Flag = False

    Select Case (N \ 100)
        Case 0: Buf = "": Flag = False
        Case 1: Buf = One & Hundred: Flag = True
        Case 2: Buf = Two & Hundred: Flag = True
        Case 3: Buf = Three & Hundred: Flag = True
        Case 4: Buf = Four & Hundred: Flag = True
        Case 5: Buf = Five & Hundred: Flag = True
        Case 6: Buf = Six & Hundred: Flag = True
        Case 7: Buf = Seven & Hundred: Flag = True
        Case 8: Buf = Eight & Hundred: Flag = True
        Case 9: Buf = Nine & Hundred: Flag = True
    End Select

    If (Flag <> False) Then N = N Mod 100
    If (N > 0) Then
        If (Flag <> False) Then Buf = Buf & " "
    Else
        EnglishDigitGroup = Buf
        Exit Function
    End If

    Select Case (N \ 10)
        Case 0, 1: Flag = False
        Case 2: Buf = Buf & "twenty": Flag = True
        Case 3: Buf = Buf & "thirty": Flag = True
        Case 4: Buf = Buf & "forty": Flag = True
        Case 5: Buf = Buf & "fifty": Flag = True
        Case 6: Buf = Buf & "sixty": Flag = True
        Case 7: Buf = Buf & "seventy": Flag = True
        Case 8: Buf = Buf & "eighty": Flag = True
        Case 9: Buf = Buf & "ninety": Flag = True
    End Select

    If (Flag <> False) Then N = N Mod 10
    If (N > 0) Then
        If (Flag <> False) Then Buf = Buf & "-"
    Else
        EnglishDigitGroup = Buf
        Exit Function
    End If

    Select Case (N)
        Case 0:
        Case 1: Buf = Buf & One
        Case 2: Buf = Buf & Two
        Case 3: Buf = Buf & Three
        Case 4: Buf = Buf & Four
        Case 5: Buf = Buf & Five
        Case 6: Buf = Buf & Six
        Case 7: Buf = Buf & Seven
        Case 8: Buf = Buf & Eight
        Case 9: Buf = Buf & Nine
        Case 10: Buf = Buf & "ten"
        Case 11: Buf = Buf & "eleven"
        Case 12: Buf = Buf & "twelve"
        Case 13: Buf = Buf & "thirteen"
        Case 14: Buf = Buf & "fourteen"
        Case 15: Buf = Buf & "fifteen"
        Case 16: Buf = Buf & "sixteen"
        Case 17: Buf = Buf & "seventeen"
        Case 18: Buf = Buf & "eighteen"
        Case 19: Buf = Buf & "nineteen"
    End Select

    EnglishDigitGroup = Buf

End Function