Code Golf: Number to Words

Question

The code golf series seem to be fairly popular. I ran across some code that converts a number to its word representation. Some examples would be (powers of 2 for programming fun):

• 2 -> Two
• 1024 -> One Thousand Twenty Four
• 1048576 -> One Million Forty Eight Thousand Five Hundred Seventy Six

The algorithm my co-worker came up was almost two hundred lines long. Seems like there would be a more concise way to do it.

Current guidelines:

• Submissions in any programming language welcome (I apologize to PhiLho for the initial lack of clarity on this one)
• Max input of 2^64 (see following link for words, thanks mmeyers)
• Short scale with English output preferred, but any algorithm is welcome. Just comment along with the programming language as to the method used.

Answer 1

I can't find the file now, but this was an Intro to Programming problem (late in the term) where I went to school. We had to be able to turn a float into a valid written number for use on a check.

After the assignment was completed the professor showed some C++ code that solved the problem using only concepts we'd already covered. It ran just 43 lines, and was well-documented.

Answer 2

Is this cheating?

perl -MNumber::Spell -e 'print spell_number(2);'

Answer 3

Lisp, using only standard functions:

(format nil "~r" 1234) ==> "one thousand two hundred thirty-four"

Bonus:

(format nil "~@r" 1234)  ==> "MCCXXXIV"

Answer 4

Here's a relatively straightforward implementation in C (52 lines).

NOTE: this does not perform any bounds checking; the caller must ensure that the calling buffer is large enough.

#include <stdio.h>
#include <string.h>

const char *zero_to_nineteen[20] = {"", "One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine ", "Ten ", "Eleven ", "Twelve ", "Thirteen ", "Fourteen ", "Fifteen ", "Sixteen ", "Seventeen ", "Eighteen ", "Nineteen "};

const char *twenty_to_ninety[8] = {"Twenty ", "Thirty ", "Forty ", "Fifty ", "Sixty ", "Seventy ", "Eighty ", "Ninety "};

const char *big_numbers[7] = {"", "Thousand ", "Million ", "Billion ", "Trillion ", "Quadrillion ", "Quintillion "};

void num_to_word(char *buf, unsigned long long num)
{
  unsigned long long power_of_1000 = 1000000000000000000ull;
  int power_index = 6;

  if(num == 0)
  {
    strcpy(buf, "Zero");
    return;
  }

  buf[0] = 0;

  while(power_of_1000 > 0)
  {
    int group = num / power_of_1000;
    if(group >= 100)
    {
      strcat(buf, zero_to_nineteen[group / 100]);
      strcat(buf, "Hundred ");
      group %= 100;
    }

    if(group >= 20)
    {
      strcat(buf, twenty_to_ninety[group / 10 - 2]);
      group %= 10;
    }

    if(group > 0)
      strcat(buf, zero_to_nineteen[group]);

    if(num >= power_of_1000)
      strcat(buf, big_numbers[power_index]);

    num %= power_of_1000;
    power_of_1000 /= 1000;
    power_index--;
  }

  buf[strlen(buf) - 1] = 0;
}

And here's a much more obfuscated version of that (682 characters). It could probably be pared down a little more if I really tried.

#include <string.h>
#define C strcat(b,
#define U unsigned long long
char*z[]={"","One","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"},*t[]={"Twenty ","Thirty ","Forty ","Fifty ","Sixty ","Seventy ","Eighty ","Ninety "},*q[]={"","Thousand ","Million ","Billion ","Trillion ","Quadrillion ","Quintillion "};
void W(char*b,U n){U p=1000000000000000000ull;int i=6;*b=0;if(!n)strcpy(b,"Zero ");else while(p){int g=n/p;if(g>99){C z[g/100]);C " ");C "Hundred ");g%=100;}if(g>19){C t[g/10-2]);g%=10;}if(g)C z[g]),C " ");if(n>=p)C q[i]);n%=p;p/=1000;i--;}b[strlen(b)-1]=0;}

Answer 5

C++, 15 lines:

#include <string>
using namespace std;

string Thousands[] = { "zero", "thousand", "million", "billion", "trillion", "quadrillion", "quintillion", "sexillion", "septillion", "octillion", "nonillion", "decillion" };
string Ones[] = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
string Tens[] = { "zero", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" };
string concat(bool cond1, string first, bool cond2, string second) { return (cond1 ? first : "") + (cond1 && cond2 ? " " : "") + (cond2 ? second : ""); }

string toStringBelowThousand(unsigned long long n) {
  return concat(n >= 100, Ones[n / 100] + " hundred", n % 100 != 0, (n % 100 < 20 ? Ones[n % 100] : Tens[(n % 100) / 10] + (n % 10 > 0 ? " " + Ones[n % 10] : "")));
}

string toString(unsigned long long n, int push = 0) {
  return n == 0 ? "zero" : concat(n >= 1000, toString(n / 1000, push + 1), n % 1000 != 0, concat(true, toStringBelowThousand(n % 1000), push > 0, Thousands[push]));
}

Usage:

cout << toString(51351);   // => fifty one thousand three hundred fifty one

Answer 6

Mmm, you might have put the bar a bit high, both on the limit (18,446,744,073,709,552,000, I don't even know how to write that!) and on the goal (the other code golfs resulted in short code, this one will be long at least for the data (words)).

Anyway, for the record, I give an well known solution (not mine!) for French, in PHP: Écriture des nombres en français. :-)

Note the ambiguity (voluntary or not) of your wording: "Submissions in any language welcome"
I first took it as "natural language", before understand you probably meant "programming language...
The algorithm is probably simpler in English (and with less regional variants...).

Answer 7

Python, 446 bytes. All lines under 80 columns, dammit. This is Paul Fisher's solution with coding tweaks on almost every line, down from his 488-byte version; he's since squeezed out several more bytes, and I concede. Go vote for his answer!

g=lambda n:["zero"," ".join(w(n,0))][n>0]
w=lambda n,l:w(n//m,l+1)+[e,z[n%m//100]+["hundred"]][n%m//100>0]+\
(p("twen thir fo"+r,"ty")[n%100//10-2]+z[n%10]if n%100>19 else z[n%100])+\
[e,k[l]][n%m>0]if n else e
p=lambda a,b:[[i+b]for i in a.split()]
e=[];r="r fif six seven eigh nine";m=1000
k=[e,["thousand"]]+p("m b tr quadr quint","illion")
z=[e]+p("one two three four five six seven eight nine ten eleven twelve","")+\
p("thir fou"+r,"teen")

The history has gotten complicated. I started with the unobfuscated code below, which supports negative numbers and range-checking, plus dashes in some numbers for better English:

>>> n2w(2**20)
'one million forty-eight thousand five hundred seventy-six'

def n2w(n):
    if n < 0:  return 'minus ' + n2w(-n)
    if n < 10: return W('zero one two three four five six seven eight nine')[n]
    if n < 20: return W('ten eleven twelve',
                        'thir four fif six seven eigh nine',
                        'teen')[n-10]
    if n < 100: 
        tens = W('', 'twen thir for fif six seven eigh nine', 'ty')[n//10-2]
        return abut(tens, '-', n2w(n % 10))
    if n < 1000:
        return combine(n, 100, 'hundred')
    for i, word in enumerate(W('thousand', 'm b tr quadr quint', 'illion')):
        if n < 10**(3*(i+2)):
            return combine(n, 10**(3*(i+1)), word)
    assert False

def W(b, s='', suff=''): return b.split() + [s1 + suff for s1 in s.split()]
def combine(n, m, term): return abut(n2w(n // m) + ' ' + term, ' ', n2w(n % m))
def abut(w10, sep, w1):  return w10 if w1 == 'zero' else w10 + sep + w1

Then I squeezed it to about 540 bytes via obfuscation (new to me), and Paul Fisher found a shorter algorithm (dropping the dashes) along with some marvelously horrible Python coding tricks. I stole the coding tricks to get down to 508 (which still did not win). I tried restarting fresh with a new algorithm, which was unable to beat Fisher's. Finally here's the tweak of his code. Respect!

The obfuscated code has been tested against the clean code, which was checked by eyeball on a bunch of cases.

Answer 8

A T-SQL (SQL Server 2005) function, including test cases:

if exists (select 1 from sys.objects where object_id = object_id(N'dbo.fnGetNumberString'))
    drop function fnGetNumberString
go

/*
Tests:
declare @tests table ( testValue bigint )
insert into @tests select -43213 union select -5 union select 0 union select 2 union select 15 union select 33 union select 100 union select 456 union select 1024 union select 10343 union select 12345678901234 union select -3434343434343

select testValue, dbo.fnGetNumberString(testValue) as textValue
from @tests
*/

create function dbo.fnGetNumberString
(
    @value bigint
)
returns nvarchar(1024)
as
begin
    if @value = 0 return 'zero' -- lets me avoid special-casing this later

    declare @isNegative bit
    set @isNegative = 0

    if @value < 0
     select @isNegative = 1, @value = @value * -1

    declare @groupNames table ( groupOrder int, groupName nvarchar(15) )
    insert into @groupNames select 1, '' union select 2, 'thousand' union select 3, 'million' union select 4, 'billion' union select 5, 'trillion' union select 6, 'quadrillion' union select 7, 'quintillion' union select 8, 'sextillion'

    declare @digitNames table ( digit tinyint, digitName nvarchar(10) )
    insert into @digitNames select 0, '' union select 1, 'one' union select 2, 'two' union select 3, 'three' union select 4, 'four' union select 5, 'five' union select 6, 'six' union select 7, 'seven' union select 8, 'eight' union select 9, 'nine' union select 10, 'ten' union select 11, 'eleven' union select 12, 'twelve' union select 13, 'thirteen' union select 14, 'fourteen' union select 15, 'fifteen' union select 16, 'sixteen' union select 17, 'seventeen' union select 18, 'eighteen' union select 19, 'nineteen'

    declare @tensGroups table ( digit tinyint, groupName nvarchar(10) )
    insert into @tensGroups select 2, 'twenty' union select 3, 'thirty' union select 4, 'forty' union select 5, 'fifty' union select 6, 'sixty' union select 7, 'seventy' union select 8, 'eighty' union select 9, 'ninety'

    declare @groups table ( groupOrder int identity, groupValue int )

    declare @convertedValue varchar(50)

    while @value > 0
    begin
     insert into @groups (groupValue) select @value % 1000

     set @value = @value / 1000
    end

    declare @returnValue nvarchar(1024)
    set @returnValue = ''

    if @isNegative = 1 set @returnValue = 'negative'

    select @returnValue = @returnValue +
     case when len(h.digitName) > 0 then ' ' + h.digitName + ' hundred' else '' end +
     case when len(isnull(t.groupName, '')) > 0 then ' ' + t.groupName + case when len(isnull(o.digitName, '')) > 0 then '-' else '' end + isnull(o.digitName, '') else case when len(isnull(o.digitName, '')) > 0 then ' ' + o.digitName else '' end end +
     case when len(n.groupName) > 0 then ' ' + n.groupName else '' end
    from @groups g
     join @groupNames n on n.groupOrder = g.groupOrder
     join @digitNames h on h.digit = (g.groupValue / 100)
     left join @tensGroups t on t.digit = ((g.groupValue % 100) / 10)
     left join @digitNames o on o.digit = case when (g.groupValue % 100) < 20 then g.groupValue % 100 else g.groupValue % 10 end
    order by g.groupOrder desc

    return @returnValue
end
go

Answer 9

See recursive's better answer. It's way betterer.

Mad props to Darius for inspiration on this one. Your big-W (now my p) was especially clever.

w=lambda n:["zero"," ".join(_(n,0))][n>0]
_=lambda n,l:_(n//M,l+1)+[E,Z[n%M//C]+["hundred"]][n%M//C>0]+\
(p("twen thir fo"+R,"ty")[n%C//10-2]+Z[n%10]if n%C>19 else Z[n%C])+\
[E,([E,["thousand"]]+p("m b tr quadr quint","illion"))[l]][n%M>0]if n else E
p=lambda a,b:[[i+b]for i in a.split()]
E=[];R="r fif six seven eigh nine";M=1000;C=100
Z=[E]+p("one two three four five six seven eight nine ten eleven twelve","")+\
p("thir fou"+R,"teen")

I test it with this:

if __name__ == "__main__":
    import sys
    print w(int(sys.argv[1]))
    assert(w(100)=="one hundred")
    assert(w(1000000)=="one million")
    assert(w(1024)=="one thousand twenty four")
    assert(w(1048576)=="one million forty eight thousand five hundred seventy six")

At this point, this is a tweak of Darius' current solution, which is in turn a tweak of my older one, which was inspired by his, and he gave some bug hints in the comments. It is also a crime against Python.

Spoilers below, rot13'd for your protection, because half the fun of golf figuring out how. I highly recommend the mnenhy Firefox extension to decode this (and other simple encoding schemes) inline.

Pbafgnagf (V eranzrq gurz guvf erivfvba gb ubcrshyyl znxr gurz pyrnere.)

• R: Gur rzcgl frg.
• E: Gung juvpu vf va pbzzba orgjrra pbhagvat va gur "grraf" (egrra, svsgrra, fvkgrra...) naq va gur graf (egl, svsgl, fvkgl....)
• Z, P: Jung gurl ner va Ebzna ahzrenyf.
• M: Nyy gur ahzoref sebz bar gb gjragl.

Shapgvbaf (fbzr nyfb eranzrq guvf ebhaq)

• j: Gur choyvp-snpvat shapgvba, juvpu gheaf n ahzore vagb jbeqf.
• _: Erphefviryl gheaf gur ahzore vagb jbeqf, gubhfnaq-ol-gubhfnaq. a vf gur ahzore, y vf ubj sne guebhtu gur cbjref bs 1000 jr ner. Ergheaf n yvfg bs fvatyrgba yvfgf bs rnpu jbeq va gur ahzore, r.t. [['bar'],['gubhfnaq'],['gjragl'],['sbhe']].
• c: sbe rnpu jbeq va gur fcnpr-frcnengrq jbeq yvfg n, nccraqf o nf n fhssvk naq chgf gurz rnpu vagb n fvatyrgba yvfg. Sbe rknzcyr, c("z o ge","vyyvba") == [['zvyyvba'],['ovyyvba'],['gevyyvba']].

Answer 10

Ok, here's F#, trying to stay readable, at about 830 bytes:

#light
let thou=[|"";"thousand";"million";"billion";"trillion";"quadrillion";"quintillion"|]
let ones=[|"";"one";"two";"three";"four";"five";"six";"seven";"eight";"nine";"ten";"eleven";
  "twelve";"thirteen";"fourteen";"fifteen";"sixteen";"seventeen";"eighteen";"nineteen"|]
let tens=[|"";"";"twenty";"thirty";"forty";"fifty";"sixty";"seventy";"eighty";"ninety"|]
let (^-) x y = if y="" then x else x^"-"^y
let (^+) x y = if y="" then x else x^" "^y
let (^?) x y = if x="" then x else x^+y
let (+^+) x y = if x="" then y else x^+y
let Tiny n = if n < 20 then ones.[n] else tens.[n/10] ^- ones.[n%10]
let Small n = (ones.[n/100] ^? "hundred") +^+ Tiny(n%100)
let rec Big n t = if n = 0UL then "" else
  (Big (n/1000UL) (t+1)) +^+ (Small(n%1000UL|>int) ^? thou.[t])
let Convert n = if n = 0UL then "zero" else Big n 0

and here are the unit tests

let Show n = 
    printfn "%20u -> \"%s\"" n (Convert n)

let tinyTests = [0; 1; 10; 11; 19; 20; 21; 30; 99] |> List.map uint64
let smallTests = tinyTests @ (tinyTests |> List.map (fun n -> n + 200UL))
let MakeTests t1 t2 = 
    List.map (fun n -> n * (pown 1000UL t1)) smallTests
    |> List.map_concat (fun n -> List.map (fun x -> x * (pown 1000UL t2) + n) smallTests)
for n in smallTests do
    Show n
for n in MakeTests 1 0 do
    Show n
for n in MakeTests 5 2 do
    Show n            
Show 1000001000678000001UL
Show 17999999999999999999UL

Answer 11

Ok, I think it's time for my own implementation in Windows BATCH script (should work on Windows 2000 or later).

Here is the code:

@echo off

set zero_to_nineteen=Zero One Two Three Four Five Six Seven Eight Nine Ten Eleven Twelve Thirteen Fourteen Fifteen Sixteen Seventeen Eighteen Nineteen
set twenty_to_ninety=ignore ignore Twenty Thirty Forty Fifty Sixty Seventy Eighty Ninety
set big_numbers=ignore Thousand Million Billion Trillion Quadrillion Quintillion Sextillion Septillion Octillion Nonillion Decillion Undecillion Duodecillion Tredecillion Quattuordecillion Quindecillion Sexdecillion Septendecillion Octodecillion Novemdecillion Vigintillion
rem             10^0   10^3     10^6    10^9    10^12    10^15       10^18       10^21      10^24      10^27     10^30     10^33     10^36       10^39        10^42        10^45             10^48         10^51        10^54           10^57         10^60          10^63

call :parse_numbers %*

exit /B 0

:parse_numbers
    :parse_numbers_loop
        if "$%~1" == "$" goto parse_numbers_end
        call :parse_number %~1
        echo %~1 -^> %parse_number_result%
        shift
        goto parse_numbers_loop
    :parse_numbers_end
    exit /B 0

:parse_number
    call :get_sign %~1
    set number_sign=%get_sign_result%
    call :remove_groups %get_sign_result_number%
    call :trim_leading_zeros %remove_groups_result%
    set number=%trim_leading_zeros_result%
    if "$%number%" == "$0" (
        set parse_number_result=Zero
        exit /B 0
    )
    set counter=0
    set parse_number_result=
    :parse_number_loop
        set last_three=%number:~-3%
        set number=%number:~0,-3%
        call :parse_three %last_three%
        call :get_from %counter% %big_numbers%
        if "$%get_from_result%" == "$" (
            set parse_number_result=* ERR: the number is too big! Even wikipedia doesn't know how it's called!
            exit /B 0
        )
        if not "$%parse_three_result%" == "$Zero" (
            if %counter% == 0 (
                set parse_number_result=%parse_three_result%
            ) else (
                if not "$%parse_number_result%" == "$" (
                    set parse_number_result=%parse_three_result% %get_from_result% %parse_number_result%
                ) else (
                    set parse_number_result=%parse_three_result% %get_from_result%
                )
            )
        )
        set /A counter+=1
        if not "$%number%" == "$" goto parse_number_loop
    if "$%parse_number_result%" == "$" (
        set parse_number_result=Zero
        exit /B 0
    ) else if not "$%number_sign%" == "$" (
        set parse_number_result=%number_sign% %parse_number_result%
    )
    exit /B 0

:parse_three
    call :trim_leading_zeros %~1
    set three=%trim_leading_zeros_result%
    set /A three=%three% %% 1000
    set /A two=%three% %% 100
    call :parse_two %two%
    set parse_three_result=
    set /A digit=%three% / 100
    if not "$%digit%" == "$0" (
        call :get_from %digit% %zero_to_nineteen%
    )
    if not "$%digit%" == "$0" (
        if not "$%get_from_result%" == "$Zero" (
            set parse_three_result=%get_from_result% Hundred
        )
    )
    if "$%parse_two_result%" == "$Zero" (
        if "$%parse_three_result%" == "$" (
            set parse_three_result=Zero
        )
    ) else (
        if "$%parse_three_result%" == "$" (
            set parse_three_result=%parse_two_result%
        ) else (
            set parse_three_result=%parse_three_result% %parse_two_result%
        )
    )
    exit /B 0

:parse_two
    call :trim_leading_zeros %~1
    set two=%trim_leading_zeros_result%
    set /A two=%two% %% 100
    call :get_from %two% %zero_to_nineteen%
    if not "$%get_from_result%" == "$" (
        set parse_two_result=%get_from_result%
        goto parse_two_20_end
    )
    set /A digit=%two% %% 10
    call :get_from %digit% %zero_to_nineteen%
    set parse_two_result=%get_from_result%
    set /A digit=%two% / 10
    call :get_from %digit% %twenty_to_ninety%
    if not "$%parse_two_result%" == "$Zero" (
        set parse_two_result=%get_from_result% %parse_two_result%
    ) else (
        set parse_two_result=%get_from_result%
    )
    goto parse_two_20_end
    :parse_two_20_end
    exit /B 0

:get_from
    call :trim_leading_zeros %~1
    set idx=%trim_leading_zeros_result%
    set /A idx=0+%~1
    shift
    :get_from_loop
        if "$%idx%" == "$0" goto get_from_loop_end
        set /A idx-=1
        shift
        goto get_from_loop
    :get_from_loop_end
    set get_from_result=%~1
    exit /B 0

:trim_leading_zeros
    set str=%~1
    set trim_leading_zeros_result=
    :trim_leading_zeros_loop
        if not "$%str:~0,1%" == "$0" (
            set trim_leading_zeros_result=%trim_leading_zeros_result%%str%
            exit /B 0
        )
        set str=%str:~1%
        if not "$%str%" == "$" goto trim_leading_zeros_loop
    if "$%trim_leading_zeros_result%" == "$" set trim_leading_zeros_result=0
    exit /B 0

:get_sign
    set str=%~1
    set sign=%str:~0,1%
    set get_sign_result=
    if "$%sign%" == "$-" (
        set get_sign_result=Minus
        set get_sign_result_number=%str:~1%
    ) else if "$%sign%" == "$+" (
        set get_sign_result_number=%str:~1%
    ) else (
        set get_sign_result_number=%str%
    )
    exit /B 0

:remove_groups
    set str=%~1
    set remove_groups_result=%str:'=%
    exit /B 0

This is the test script I used:

@echo off
rem 10^x:x= 66  63  60  57  54  51  48  45  42  39  36  33  30  27  24  21  18  15  12   9   6   3   0
call number                                                                                          0
call number                                                                                          2
call number                                                                                        -17
call number                                                                                         30
call number                                                                                         48
call number                                                                                       -256
call number                                                                                        500
call number                                                                                        874
call number                                                                                      1'024
call number                                                                                    -17'001
call number                                                                                    999'999
call number                                                                                  1'048'576
call number                                                                         -1'000'001'000'000
call number                                                                    912'345'014'587'957'003
call number                                                       -999'912'345'014'587'124'337'999'999
call number                                        111'222'333'444'555'666'777'888'999'000'000'000'001
call number                               -912'345'014'587'912'345'014'587'124'912'345'014'587'124'337
call number    999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999
call number  1'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000
rem 10^x:x= 66  63  60  57  54  51  48  45  42  39  36  33  30  27  24  21  18  15  12   9   6   3   0

And this is the output I got from my test script:

0 -> Zero
2 -> Two
-17 -> Minus Seventeen
30 -> Thirty
48 -> Forty Eight
-256 -> Minus Two Hundred Fifty Six
500 -> Five Hundred
874 -> Eight Hundred Seventy Four
1'024 -> One Thousand Twenty Four
-17'001 -> Minus Seventeen Thousand One
999'999 -> Nine Hundred Ninety Nine Thousand Nine Hundred Ninety Nine
1'048'576 -> One Million Forty Eight Thousand Five Hundred Seventy Six
-1'000'001'000'000 -> Minus One Trillion One Million
912'345'014'587'957'003 -> Nine Hundred Twelve Quadrillion Three Hundred Forty Five Trillion Fourteen Billion Five Hundred Eighty Seven Million Nine Hundred Fifty Seven Thousand Three
-999'912'345'014'587'124'337'999'999 -> Minus Nine Hundred Ninety Nine Septillion Nine Hundred Twelve Sextillion Three Hundred Forty Five Quintillion Fourteen Quadrillion Five Hundred Eighty Seven Trillion One Hundred Twenty Four Billion Three Hundred Thirty Seven Million Nine Hundred Ninety Nine Thousand Nine Hundred Ninety Nine
111'222'333'444'555'666'777'888'999'000'000'000'001 -> One Hundred Eleven Undecillion Two Hundred Twenty Two Decillion Three Hundred Thirty Three Nonillion Four Hundred Forty Four Octillion Five Hundred Fifty Five Septillion Six Hundred Sixty Six Sextillion Seven Hundred Seventy Seven Quintillion Eight Hundred Eighty Eight Quadrillion Nine Hundred Ninety Nine Trillion One
-912'345'014'587'912'345'014'587'124'912'345'014'587'124'337 -> Minus Nine Hundred Twelve Tredecillion Three Hundred Forty Five Duodecillion Fourteen Undecillion Five Hundred Eighty Seven Decillion Nine Hundred Twelve Nonillion Three Hundred Forty Five Octillion Fourteen Septillion Five Hundred Eighty Seven Sextillion One Hundred Twenty Four Quintillion Nine Hundred Twelve Quadrillion Three Hundred Forty Five Trillion Fourteen Billion Five Hundred Eighty Seven Million One Hundred Twenty Four Thousand Three Hundred Thirty Seven
999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999'999 -> Nine Hundred Ninety Nine Vigintillion Nine Hundred Ninety Nine Novemdecillion Nine Hundred Ninety Nine Octodecillion Nine Hundred Ninety Nine Septendecillion Nine Hundred Ninety Nine Sexdecillion Nine Hundred Ninety Nine Quindecillion Nine Hundred Ninety Nine Quattuordecillion Nine Hundred Ninety Nine Tredecillion Nine Hundred Ninety Nine Duodecillion Nine Hundred Ninety Nine Undecillion Nine Hundred Ninety Nine Decillion Nine Hundred Ninety Nine Nonillion Nine Hundred Ninety Nine Octillion Nine Hundred Ninety Nine Septillion Nine Hundred Ninety Nine Sextillion Nine Hundred Ninety Nine Quintillion Nine Hundred Ninety Nine Quadrillion Nine Hundred Ninety Nine Trillion Nine Hundred Ninety Nine Billion Nine Hundred Ninety Nine Million Nine Hundred Ninety Nine Thousand Nine Hundred Ninety Nine
1'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000 -> * ERR: the number is too big! Even wikipedia doesn't know how it's called!

If I could find some more names of large numbers, the script would support even bigger numbers. Currently, though, the script will work with all numbers from -(10^66-1) to (10^66-1).

I have to mention, that I had a lot of fun solving this in BATCH. :)

Answer 12

Here's a Scala solution. I'm not happy about trying to make it look short -- I sacrificed a bit of readability :(

object NumSpeller {
  val digits = Array("","one","two","three","four","five","six","seven","eight","nine")
  val teens = Array("ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen")
  val tens = Array("", "ten", "twenty", "thirty", "fourty", "fifty", "sixty", "seventy", "eighty", "ninety")
  val thousands = Array("", "thousand", "million", "billion", "trillion", "quadrillion", "quintillion")

  def spellGroup(num:Int) = {
    val (v3, v2, v1) = ((num / 100) % 10, (num / 10) % 10, num % 10)
    val hs = v3 match { case 0 => ""; case d => digits(d) + " hundred " }
    val ts = v2 match {
      case 0 => digits(v1)
      case 1 => teens(v1)
      case _ => v3 match { case 0 => tens(v2); case _ => tens(v2) + "-" + digits(v1) }
    }
    hs + ts
  }

  def numberGroups(num:Long) = {
    def _numberGroups(num:Long, factor:Int):List[(Double,Int)] = factor match {
      case 0 => List((num % 1000,0))
      case _ => ((num / Math.pow(1000, factor)) % 1000, factor) :: _numberGroups(num, factor - 1)
    }
    val ints = _numberGroups(num, 6) map (x => (x._1.asInstanceOf[Int],x._2))
    ints dropWhile (x => x._1 == 0.0)
  }

  def spell(num:Long) = num match { case 0 => "zero"; case _ => (numberGroups(num) map { x => spellGroup(x._1) + " " + thousands(x._2) + " " }).mkString.trim  }
}

Usage is:

NumSpeller.spell(458582)

Answer 13

Perl 5.10

my %expo=(0,'',
  qw'1 thousand 2 million 3 billion 4 trillion 5 quadrillion 6 quintillion
  7 sextillion 8 septillion 9 octillion 10 nonillion 11 decillion 12 undecillion
  13 duodecillion 14 tredecillion 15 quattuordecillion 16 quindecillion
  17 sexdecillion 18 septendecillion 19 octodecillion 20 novemdecillion
  21 vigintillion'
);

my %digit=(0,'',
  qw'1 one 2 two 3 three 4 four 5 five 6 six 7 seven 8 eight 9 nine 10 ten
  11 eleven 12 twelve 13 thirteen 14 fourteen 15 fifteen 16 sixteen 17 seventeen
  18 eighteen 19 nineteen 2* twenty 3* thirty 4* forty 5* fifty 6* sixty
  7* seventy 8* eighty 9* ninety'
);

sub spell_number(_){
  local($_)=@_;
  ($_,@_)=split/(?=(?:.{3})*+$)/;
  $_=0 x(3-length).$_;
  unshift@_,$_;
  my @o;
  my $c=@_;
  for(@_){
    my $o='';
    /(.)(.)(.)/;
    $o.=$1?$digit{$1}.' hundred':'';
    $o.=$2==1?
      ' '.$digit{$2.$3}
    :
      ($2?' '.$digit{"$2*"}:'').
      ($2&&$3?' ':'').
      $digit{$3}
    ;
    $o.=--$c?($o?' '.$expo{$c}.', ':''):'';
    push@o,$o;
  }
  my $o;
  $o.=$_ for@o;
  $o=~/^\s*+(.*?)(, )?$/;
  $o?$1:'zero';
}

Notes:

• This almost works on earlier Perls, it's that first split() that seems to be the main problem. As it sits now the strings take up the bulk of the characters.
• I could have shortened it, by removing the my's, and the local, as well as putting it all on one line.
• I used Number::Spell as a starting point.
• Works under strict and warnings.

Answer 14

Does anyone plan on adding the appropriate commas and 'and' any time soon? Or hyphenating twenty-one through ninety-nine? Not much point otherwise, IMHO :)

'Nine Hundred Ninety Nine Thousand Nine Hundred Ninety Nine'

vs

'Nine hundred and ninety-nine thousand, nine hundred and ninety-nine'

(And no, mine doesn't work. Yet.)

Answer 15

#!/usr/bin/env perl
my %symbols = (
1 => "One", 2 => "Two", 3 => "Three", 4 => "Four", 5 => "Five",
6 => "Six", 7 => "Seven", 8 => "Eight", 9 => "Nine", 10 => "Ten",
11 => "Eleven", 12 => "Twelve", 13 => "Thirteen", 14 => "Fourteen",
15 => "Fifteen", 16 => "Sixteen", 17 => "Seventeen", 18 => "Eighteen",
19 => "Nineteen", 20 => "Twenty", 30 => "Thirty", 40 => "Forty",
50 => "Fifty", 60 => "Sixty", 70 => "Seventy", 80 => "Eighty",
90 => "Ninety", 100 => "Hundred");

my %three_symbols = (1 => "Thousand", 2 => "Million", 3 => "Billion" );

sub babo {
my ($input) = @_;
my @threes = split(undef, $input);
my $counter = ($#threes + 1);
my $remainder = $counter % 3;
my @result;

while ($counter > 0){
    my $digits = "";
    my $three;
    my $full_match = 0;

    if ($remainder > 0){
        while ($remainder > 0) {
            $digits .= shift(@threes);
            $remainder--;
            $counter--;
        }
    }
    else {
        $digits = join('',@threes[0,1,2]);
        splice(@threes, 0, 3);
        $counter -= 3;
    }
    if (exists($symbols{$digits})){
        $three = $symbols{$digits};
        $full_match = 1;
    }
    elsif (length($digits) == 3) {
        $three = $symbols{substr($digits,0,1)};
        $three .= " Hundred";
        $digits = substr($digits,1,2);
        if (exists($symbols{$digits})){
            $three .= " " . $symbols{$digits};
            $full_match = 1;
        }
    }
    if ($full_match == 0){
        $three .= " " . $symbols{substr($digits,0,1)."0"};
        $three .= " " . $symbols{substr($digits,1,1)};
    }
    push(@result, $three);
    if ($counter > 0){
        push(@result, "Thousand");
    }
}
my $three_counter = 0;
my @r = map {$_ eq "Thousand" ? $three_symbols{++$three_counter}:$_ }
    reverse @result;
return join(" ", reverse @r);
}
print babo(1) . "\n";
print babo(12) . "\n";
print babo(120) . "\n";
print babo(1234) . "\n";
print babo(12345) . "\n";
print babo(123456) . "\n";
print babo(1234567) . "\n";
print babo(1234567890) . "\n";

Answer 16

C# - 30 lines incl. method declaration and { }s:

Takes into account all the previously aforementioned commas, ands and hyphens. I've only included up to octillion because decimal.MaxValue is only in the octillions. For bigger integers you would need to add corresponding items to the thou[] array and perhaps pass the number in as a string, modifying the line to extract the block by using the last 3 chars instead of using modulo as I have here.

    static string wordify(decimal v)
    {
        if (v == 0) return "zero";
        var units = " one two three four five six seven eight nine".Split();
        var teens = " eleven twelve thir# four# fif# six# seven# eigh# nine#".Replace("#", "teen").Split();
        var tens = " ten twenty thirty forty fifty sixty seventy eighty ninety".Split();
        var thou = " thousand m# b# tr# quadr# quint# sext# sept# oct#".Replace("#", "illion").Split();
        var g = (v < 0) ? "minus " : "";
        var w = "";
        var p = 0;
        v = Math.Abs(v);
        while (v > 0)
        {
            int b = (int)(v % 1000);
            if (b > 0)
            {
                var h = (b / 100);
                var t = (b - h * 100) / 10;
                var u = (b - h * 100 - t * 10);
                var s = ((h > 0) ? units[h] + " hundred" + ((t > 0 | u > 0) ? " and " : "") : "")
                      + ((t > 0) ? (t == 1 && u > 0) ? teens[u] : tens[t] + ((u > 0) ? "-" : "") : "")
                      + ((t != 1) ? units[u] : "");
                s = (((v > 1000) && (h == 0) && (p == 0)) ? " and " : (v > 1000) ? ", " : "") + s;
                w = s + " " + thou[p] + w;
            }
            v = v / 1000;
            p++;
        }
        return g + w;
    }

Called using:

static void Main(string[] args)
{
  Console.WriteLine(wordify(decimal.MaxValue));
}

Output:

seventy-nine octillion, two hundred and twenty-eight septillion, one hundred and sixty-two sextillion, five hundred and fourteen quintillion, two hundred and sixty-four quadrillion, three hundred and thirty-seven trillion, five hundred and ninety-three billion, five hundred and forty-three million, nine hundred and fifty thousand, three hundred and thirty-five

Answer 17

Paul Fischer and Darius: You guys have some great ideas, but I hate to see them implemented in such an overly verbose fashion. :) Just kidding, your solution is awesome, but I squeezed 14 30 more bytes out, while staying inside of 79 columns and maintaining python 3 compatibility.

So here's my 416 byte python within 79 columns: (thanks guys, I'm standing on your shoulders)

w=lambda n:_(n,["","thousand "]+p("m b tr quadr quint","illion"))[:-1]or"zero"
_=lambda n,S:n*"x"and _(n//M,S[1:])+(Z[n%M//C]+"hundred ")*(n%M//C>0)+(n%C>19
and p("twen thir fo"+R,"ty")[n%C//10-2]+Z[n%10]or Z[n%C])+S[0]*(n%M>0)
p=lambda a,b="":[i+b+" "for i in a.split()]
R="r fif six seven eigh nine"
M=1000
C=100
Z=[""]+p("one two three four five%st nine ten eleven twelve"%R[5:20])+p(
"thir fou"+R,"teen")

And the tests:

if __name__ == "__main__":
    import sys
    assert(w(0)=="zero")
    assert(w(100)=="one hundred")
    assert(w(1000000)=="one million")
    assert(w(1024)=="one thousand twenty four")
    assert(w(1048576)=="one million forty eight thousand five hundred seventy six")

Answer 18

a few years ago i created this in c#.. for multi language applications

this one is base class..

public abstract class ValueSource
{
    public abstract object Value { get; }
}

this one is for wordify..

public abstract class NumberTextValueSource:ValueSource
{
    public abstract decimal Number { get; }
    public abstract string Format { get; }
    public abstract string Negative { get; }
    public abstract bool UseValueIfZero { get; }
    public abstract string N0 { get; }
    public abstract string N1 { get; }
    public abstract string N2 { get; }
    public abstract string N3 { get; }
    public abstract string N4 { get; }
    public abstract string N5 { get; }
    public abstract string N6 { get; }
    public abstract string N7 { get; }
    public abstract string N8 { get; }
    public abstract string N9 { get; }
    public abstract string N10 { get; }
    public abstract string N11 { get; }
    public abstract string N12 { get; }
    public abstract string N13 { get; }
    public abstract string N14 { get; }
    public abstract string N15 { get; }
    public abstract string N16 { get; }
    public abstract string N17 { get; }
    public abstract string N18 { get; }
    public abstract string N19 { get; }
    public abstract string N20 { get; }
    public abstract string N30 { get; }
    public abstract string N40 { get; }
    public abstract string N50 { get; }
    public abstract string N60 { get; }
    public abstract string N70 { get; }
    public abstract string N80 { get; }
    public abstract string N90 { get; }
    public abstract string N100 { get; }
    public abstract string NHundred { get; }
    public abstract string N1000 { get; }
    public abstract string NThousand { get; }
    public abstract string NMillion { get; }
    public abstract string NBillion { get; }
    public abstract string NTrillion { get; }
    public abstract string NQuadrillion { get; }


    string getOne(Type t, string v)
    {
        if (v[0] == '0' && !UseValueIfZero)
            return "";
        return (string)t.GetProperty("N" + v[0].ToString()).GetValue(this, null);
    }
    string getTwo(Type t, string v)
    {
        if (v[0] == '0')
            if (v[1] != '0')
                return getOne(t, v.Substring(1));
            else
                return "";

        if (v[1] == '0' || v[0] == '1')
            return (string)t.GetProperty("N" + v).GetValue(this, null);

        return (string)t.GetProperty("N" + v[0].ToString() + "0").GetValue(this, null) +
               getOne(t, v.Substring(1));
    }
    string getThree(Type t, string v)
    {
        if(v[0] == '0')
            return getTwo(t,v.Substring(1));

        if (v[0] == '1')
            return
                N100 +
                getTwo(t, v.Substring(1));
        return
            getOne(t, v[0].ToString()) +
            NHundred +
            getTwo(t, v.Substring(1));
    }
    string getFour(Type t, string v)
    {
        if (v[0] == '0')
            return getThree(t, v.Substring(1));
        if (v[0] == '1')
            return
                N1000 +
                getThree(t, v.Substring(1));
        return
            getOne(t, v[0].ToString()) +
            NThousand +
            getThree(t, v.Substring(1));
    }
    string getFive(Type t, string v)
    {
        if (v[0] == '0')
            return getFour(t, v.Substring(1));
        return
            getTwo(t, v.Substring(0, 2)) +
            NThousand +
            getThree(t, v.Substring(2));
    }
    string getSix(Type t, string v)
    {
        if (v[0] == '0')
            return getFive(t, v.Substring(1));
        return
            getThree(t, v.Substring(0, 3)) +
            NThousand +
            getThree(t, v.Substring(3));
    }
    string getSeven(Type t, string v)
    {
        if (v[0] == '0')
            return getSix(t, v.Substring(1));
        return
            getOne(t, v[0].ToString()) +
            NMillion +
            getSix(t, v.Substring(3));
    }
    string getEight(Type t, string v)
    {
        if (v[0] == '0')
            return getSeven(t, v.Substring(1));
        return
            getTwo(t, v.Substring(0, 2)) +
            NMillion +
            getSix(t, v.Substring(2));
    }
    string getNine(Type t, string v)
    {
        if (v[0] == '0')
            return getEight(t, v.Substring(1));
        return
            getThree(t, v.Substring(0, 3)) +
            NMillion +
            getSix(t, v.Substring(3));
    }
    string getTen(Type t, string v)
    {
        if (v[0] == '0')
            return getNine(t, v.Substring(1));
        return
            getOne(t, v.Substring(0, 1)) +
            NBillion +
            getNine(t, v.Substring(1));
    }
    string getEleven(Type t, string v)
    {
        if (v[0] == '0')
            return getTen(t, v.Substring(1));
        return
            getTwo(t, v.Substring(0, 2)) +
            NBillion +
            getNine(t, v.Substring(2));
    }
    string getTwelve(Type t, string v)
    {
        if (v[0] == '0')
            return getEleven(t, v.Substring(1));
        return
            getThree(t, v.Substring(0, 3)) +
            NBillion +
            getNine(t, v.Substring(3));
    }
    string getThirteen(Type t, string v)
    {
        if (v[0] == '0')
            return getTwelve(t, v.Substring(1));
        return
            getOne(t, v.Substring(0, 1)) +
            NTrillion +
            getTwelve(t, v.Substring(1));
    }
    string getForteen(Type t, string v)
    {
        if (v[0] == '0')
            return getThirteen(t, v.Substring(1));
        return
            getTwo(t, v.Substring(0, 2)) +
            NTrillion +
            getTwelve(t, v.Substring(2));
    }
    string getFifteen(Type t, string v)
    {
        if (v[0] == '0')
            return getForteen(t, v.Substring(1));
        return
            getThree(t, v.Substring(0, 3)) +
            NTrillion +
            getTwelve(t, v.Substring(3));
    }
    string getSixteen(Type t, string v)
    {
        if (v[0] == '0')
            return getFifteen(t, v.Substring(1));
        return
            getOne(t, v.Substring(0, 1)) +
            NQuadrillion +
            getFifteen(t, v.Substring(1));
    }
    string getSeventeen(Type t, string v)
    {
        if (v[0] == '0')
            return getSixteen(t, v.Substring(1));
        return
            getTwo(t, v.Substring(0, 2)) +
            NQuadrillion +
            getFifteen(t, v.Substring(2));
    }
    string getEighteen(Type t, string v)
    {
        if (v[0] == '0')
            return getSeventeen(t, v.Substring(1));
        return
            getThree(t, v.Substring(0, 3)) +
            NQuadrillion +
            getFifteen(t, v.Substring(3));
    }
    string convert(Type t, string hp)
    {
        switch (hp.Length)
        {
            case 1:
                return getOne(t, hp);
            case 2:
                return getTwo(t, hp);
            case 3:
                return getThree(t, hp);
            case 4:
                return getFour(t, hp);
            case 5:
                return getFive(t, hp);
            case 6:
                return getSix(t, hp);
            case 7:
                return getSeven(t, hp);
            case 8:
                return getEight(t, hp);
            case 9:
                return getNine(t, hp);
            case 10:
                return getTen(t, hp);
            case 11:
                return getEleven(t, hp);
            case 12:
                return getTwelve(t, hp);
            case 13:
                return getThirteen(t, hp);
            case 14:
                return getForteen(t, hp);
            case 15:
                return getFifteen(t, hp);
            case 16:
                return getSixteen(t, hp);
            case 17:
                return getSeventeen(t, hp);
            case 18:
                return getEighteen(t, hp);
        }
        return "";
    }
    public override object Value
    {
        get 
        {
            decimal d = Number;
            decimal highPoint, lowPoint;
            bool isNeg = d < 0;
            d = Math.Abs(d);
            highPoint = Math.Floor(d);
            lowPoint = d - highPoint;
            Type t = this.GetType();

            string strHigh = convert(t, highPoint.ToString()),
                    strLow =
                       lowPoint > 0 ?
                       convert(t, lowPoint.ToString().Substring(2)) :
                       UseValueIfZero ? N0 : "";
            if (isNeg) strHigh = Negative + " " + strHigh;
            return string.Format(Format, strHigh, strLow);
        }
    }
}

and this one is for Turkish Lera (TRY)

public class TRYNumberTextValueSource:NumberTextValueSource
{
    decimal num;
    public TRYNumberTextValueSource(decimal value)
    {
        num = Math.Round(value, 2);
    }
    public override decimal Number
    {
        get { return num; }
    }

    public override string Format
    {
        get 
        {
            if (num == 0)
                return N0 + " YTL";
            if (num > -1 && num < 1)
                return "{0}{1} Kuruş";
            return "{0} YTL {1} Kuruş"; 
        }
    }

    public override string Negative
    {
        get { return "-"; }
    }

    public override bool UseValueIfZero
    {
        get { return false; }
    }

    public override string N0
    {
        get { return "sıfır"; }
    }

    public override string N1
    {
        get { return "bir"; }
    }

    public override string N2
    {
        get { return "iki"; }
    }

    public override string N3
    {
        get { return "üç"; }
    }

    public override string N4
    {
        get { return "dört"; }
    }

    public override string N5
    {
        get { return "beş"; }
    }

    public override string N6
    {
        get { return "altı"; }
    }

    public override string N7
    {
        get { return "yedi"; }
    }

    public override string N8
    {
        get { return "sekiz"; }
    }

    public override string N9
    {
        get { return "dokuz"; }
    }

    public override string N10
    {
        get { return "on"; }
    }

    public override string N11
    {
        get { return "onbir"; }
    }

    public override string N12
    {
        get { return "oniki"; }
    }

    public override string N13
    {
        get { return "onüç"; }
    }

    public override string N14
    {
        get { return "ondört"; }
    }

    public override string N15
    {
        get { return "onbeş"; }
    }

    public override string N16
    {
        get { return "onaltı"; }
    }

    public override string N17
    {
        get { return "onyedi"; }
    }

    public override string N18
    {
        get { return "onsekiz"; }
    }

    public override string N19
    {
        get { return "ondokuz"; }
    }

    public override string N20
    {
        get { return "yirmi"; }
    }

    public override string N30
    {
        get { return "otuz"; }
    }

    public override string N40
    {
        get { return "kırk"; }
    }

    public override string N50
    {
        get { return "elli"; }
    }

    public override string N60
    {
        get { return "altmış"; }
    }

    public override string N70
    {
        get { return "yetmiş"; }
    }

    public override string N80
    {
        get { return "seksen"; }
    }

    public override string N90
    {
        get { return "doksan"; }
    }

    public override string N100
    {
        get { return "yüz"; }
    }

    public override string NHundred
    {
        get { return "yüz"; }
    }

    public override string N1000
    {
        get { return "bin"; }
    }

    public override string NThousand
    {
        get { return "bin"; }
    }

    public override string NMillion
    {
        get { return "milyon"; }
    }

    public override string NBillion
    {
        get { return "milyar"; }
    }

    public override string NTrillion
    {
        get { return "trilyon"; }
    }

    public override string NQuadrillion
    {
        get { return "trilyar"; }
    }
}

and this is usage :

MessageBox.show((string)(new TRYNumberTextValueSource(12345)).Value);

Answer 19

In the D programming language

string Number(ulong i)
{
    static string[] names = [
      ""[],
      " thousand",
      " million",
      " billion",
      " trillion",
      " quadrillion",
      ];
    string ret = null;
    foreach(mult; names)
    {
       if(i%1000 != 0)
       {
           if(ret != null) ret = ret ~ ", "
           ret = Cent(i%1000) ~ mult ~ ret;
       }
       i /= 1000;
    }
    return ret;
}

string Cent(int i)
{
   static string[] v = 
        [""[], "one", "two", "three", "four", 
        "five", "six", "seven", "eight", "nine"];

   static string[] tens = 
        ["!"[], "!", "twenty", "thirty", "forty", 
        "fifty", "sixty", "seventy", "eighty", "ninety"];

   string p1, p2, p3 = "";


   if(i >= 100)
   {
      p1 = v[i/100] ~ " hundred";
      p3 = (i % 100 != 0) ? " and " : ""; //optional
   }
   else
      p1 = "";

   i %= 100;
   switch(i)
   {
       case 0, 1, 2, 3, 4, 5, 6, 7, 8, 9:
          p2 = v[i];
          break;

       case 10: p2 = "ten"; break;
       case 11: p2 = "eleven"; break;
       case 12: p2 = "twelve"; break;
       case 13: p2 = "thirteen"; break;
       case 14: p2 = "fourteen"; break;
       case 15: p2 = "fifteen"; break;
       case 16: p2 = "sixteen"; break;
       case 17: p2 = "seventeen"; break;
       case 18: p2 = "eighteen"; break;
       case 19: p2 = "nineteen"; break;

       default:
           p2 = tens[i/10] ~ "-" ~ v[i%10];
           break;

   }

   return p1 ~ p3 ~ p2;
}

import std.stdio;
void main()
{
  writef("%s\n", Number(8_000_400_213));
}

Try it out here

Answer 20

In A86 assember - assembles to a .COM executable:

dd 0ba02c6bfh, 0b8bd10c1h, 0e808b512h, 0ea870100h, 08700e9e8h, 010273eah
dd 0e0e8c2h, 06b51872h, 0c000ebe8h, 0b3c02e8h, 03368067dh, 0b2e901h
dd 0baaa5004h, 0fd8110c1h, 0cd7c1630h, 0bf3031bbh, 0a0571000h, 0ec880080h
dd 0c581c589h, 023c0081h, 0e7f087ch, 0823e38h, 027b00875h, 0e901d068h
dd 0b6400080h, 04f6f603h, 080d08a1ch, 0b60f80c4h, 07f06c7f4h, 088303000h
dd 0ac00813eh, 087ef828h, 0b00056e8h, 051e81dh, 0d83850adh, 0e7f157ch
dd 0a74fc38h, 0262ce088h, 0e901a368h, 01d2c003bh, 0580036e8h, 0b7efc38h
dd 0774d838h, 0f828e088h, 0800026e8h, 0127e1dfah, 0afd448ah, 0440afe44h
dd 074f838ffh, 0e8c28a05h, 0cafe000fh, 0ab7cee39h, 05a2405c6h, 021cd09b4h
dd 05e856c3h, 020b05e00h, 0c5bec3aah, 074c00a02h, 03c80460ah, 0fefa755bh
dd 046f675c8h, 0745b3cach, 0f8ebaae8h, 0eec1d689h, 08a3c8a03h, 07e180cah
dd 0cfd2c1feh, 0ebe8c342h, 0fed8d0ffh, 0c3f775cdh, 01e581e8fh, 0303c5ea8h
dd 0df6f652ah, 078bde03ch, 05e027500h, 01ec1603ch, 07d40793dh, 0603c8080h
dd 09f6f2838h, 040f17a3dh, 080f17a22h, 0403d7264h, 0793cdee1h, 0140740f1h
dd 01e2f7d32h, 02f488948h, 0a7c43b05h, 0a257af9bh, 0be297b6ch, 04609e30ah
dd 0b8f902abh, 07c21e13eh, 09a077d9eh, 054f82ab5h, 0fabe2af3h, 08a6534cdh
dd 0d32b4c97h, 035c7c8ceh, 082bcc833h, 0f87f154fh, 0650ff7eah, 02f143fdfh
dd 0a1fd687fh, 0c3e687fdh, 0c6d50fe0h, 075f13574h, 0898c335bh, 0e748ce85h
dd 08769676fh, 0ad2cedd3h, 0928c77c7h, 077e2d18eh, 01a77e8f6h
db 0bah, 01bh

That's a 454 byte executable.

Here's the (slightly smaller) code. Since A86 is an 8086 only assembler, I've had to hand code the 32bit extensions:

 mov di,strings
 mov dx,tree_data * 8 + 1
 mov bp,code_data * 8
l1:
 mov ch,8
 call extract_bits
 xchg dx,bp
 call extract_bit
 xchg dx,bp
 jnc l2
 add dx,ax
l2:
 call extract_bit
 jc l3
 mov ch,6
 call extract_bits
 shr al,2
 cmp al,11
 push l27
 jl get_string
l25:
 add al,48+32
 stosb
l27:
 mov dx,tree_data * 8 + 1
l3:
 cmp bp,end_data * 8
 jl l1

convert:
 mov bx,'01'
 mov di,01000h
 push di

 mov al,[80h]
 mov ah,ch
 mov bp,ax
 add bp,81h
 cmp al,2
 jl zero
 jg l90
 cmp byte ptr [82h],bh
 jne l90
zero: 
 mov al,39
 push done

get_string:
 mov si,strings-1
 or al,al
 je l36
l35:
 inc si
 cmp byte ptr [si],';'+32
 jne l35
 dec al
 jnz l35
l36:
 inc si
l37:
 lodsb
 cmp al,';'+32
 je ret
 stosb
 jmp l37


l90:
 inc ax
 mov dh,3
 div dh
 add al,28
 mov dl,al
 add ah,80h
 db 0fh, 0b6h, 0f4h ; movzx si,ah
 mov word ptr [80h],'00'

l95: 
 lodsb

 sub al,bh
 jle l100
 call get_string2
 mov al,29
 call get_string2

l100:
 lodsw
 push ax
 cmp al,bl
 jl l150
 jg l140
 cmp ah,bh
 je l140

 mov al,ah
 sub al,'0'-10
 push l150

get_string2:
 push si
 call get_string
 pop si
 mov al,' '
 stosb
 ret

l140:
 sub al,'0'-19
 call get_string2

l150:
 pop ax
 cmp ah,bh
 jle l200
 cmp al,bl
 je l200
 mov al,ah
 sub al,bh
 call get_string2

l200:
 cmp dl,29
 jle l300

 mov al,[si-3]
 or al,[si-2]
 or al,[si-1]
 cmp al,bh
 je l300

 mov al,dl
 call get_string2

l300:
 dec dl
 cmp si,bp
 jl l95

done: 
 mov byte ptr [di],'$'
 pop dx
 mov ah,9
 int 21h 
 int 20h

l41:
 rcr al,1
 dec ch
 jz ret

extract_bits:
 push l41
extract_bit:
 mov si,dx
 shr si,3
 mov bh,[si]
 mov cl,dl
 and cl,7
 inc cl
 ror bh,cl
 inc dx
 ret

tree_data:
 dw 01e8fh, 01e58h, 05ea8h, 0303ch, 0652ah, 0df6fh, 0e03ch, 078bdh
 dw 07500h, 05e02h, 0603ch, 01ec1h, 0793dh, 07d40h, 08080h, 0603ch
 dw 02838h, 09f6fh, 07a3dh, 040f1h, 07a22h, 080f1h, 07264h, 0403dh
 dw 0dee1h, 0793ch, 040f1h, 01407h, 07d32h, 01e2fh, 08948h
 db 048h
code_data:
 dw 052fh, 0c43bh, 09ba7h, 057afh, 06ca2h, 0297bh, 0abeh, 09e3h
 dw 0ab46h, 0f902h, 03eb8h, 021e1h, 09e7ch, 077dh, 0b59ah, 0f82ah
 dw 0f354h, 0be2ah, 0cdfah, 06534h, 0978ah, 02b4ch, 0ced3h, 0c7c8h
 dw 03335h, 0bcc8h, 04f82h, 07f15h, 0eaf8h, 0ff7h, 0df65h, 0143fh
 dw 07f2fh, 0fd68h, 0fda1h, 0e687h, 0e0c3h, 0d50fh, 074c6h, 0f135h
 dw 05b75h, 08c33h, 08589h, 048ceh, 06fe7h, 06967h, 0d387h, 02cedh
 dw 0c7adh, 08c77h, 08e92h, 0e2d1h, 0f677h, 077e8h, 0ba1ah
 db 01bh
end_data:

strings:

The text is stored using Huffman encoding. The command line is passed as a string so converting it is simple - split the string into groups of three and parse each group (hundreds, tens and units) following each with the current multiplier (millions, thousands, etc).

Skizz

Answer 21

Here's one in php, from http://www.phpro.org/examples/Convert-Numbers-to-Words.html

convert_number(2850) returns Two Thousand Eight Hundred and Fifty

and if you want an even more awesome on that handles commas and numbers up to vigintillion check out zac hesters work at http://code.zacharyhester.com/?type=flat&lang=php&name=language

function convert_number($number) 
{ 
    if (($number < 0) || ($number > 999999999)) 
    { 
    throw new Exception("Number is out of range");
    } 

    $Gn = floor($number / 1000000);  /* Millions (giga) */ 
    $number -= $Gn * 1000000; 
    $kn = floor($number / 1000);     /* Thousands (kilo) */ 
    $number -= $kn * 1000; 
    $Hn = floor($number / 100);      /* Hundreds (hecto) */ 
    $number -= $Hn * 100; 
    $Dn = floor($number / 10);       /* Tens (deca) */ 
    $n = $number % 10;               /* Ones */ 

    $res = ""; 

    if ($Gn) 
    { 
        $res .= convert_number($Gn) . " Million"; 
    } 

    if ($kn) 
    { 
        $res .= (empty($res) ? "" : " ") . 
            convert_number($kn) . " Thousand"; 
    } 

    if ($Hn) 
    { 
        $res .= (empty($res) ? "" : " ") . 
            convert_number($Hn) . " Hundred"; 
    } 

    $ones = array("", "One", "Two", "Three", "Four", "Five", "Six", 
        "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", 
        "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eightteen", 
        "Nineteen"); 
    $tens = array("", "", "Twenty", "Thirty", "Fourty", "Fifty", "Sixty", 
        "Seventy", "Eigthy", "Ninety"); 

    if ($Dn || $n) 
    { 
        if (!empty($res)) 
        { 
            $res .= " and "; 
        } 

        if ($Dn < 2) 
        { 
            $res .= $ones[$Dn * 10 + $n]; 
        } 
        else 
        { 
            $res .= $tens[$Dn]; 

            if ($n) 
            { 
                $res .= "-" . $ones[$n]; 
            } 
        } 
    } 

    if (empty($res)) 
    { 
        $res = "zero"; 
    } 

    return $res; 
}

Answer 22

Perl & CPAN working together:

#!/usr/bin/perl

use strict;
use warnings;

use Lingua::EN::Numbers qw(num2en);

print num2en($_), "\n" for 2, 1024, 1024*1024;

C:\Temp> n.pl
two
one thousand and twenty-four
one million, forty-eight thousand, five hundred and seventy-six